All questions
Question 1
Rewrite the exponential equation 103=1000 in logarithmic form using by=x⇔logb(x)=y.
- log1000(10)=3
- log10(1000)=3 (correct answer)
- log10(3)=1000
- log3(10)=1000
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. As inverse operations, logarithms and exponents cancel each other: log_b(bx) = x for any x (the log undoes the exponent), and b^(log_b(x)) = x for x > 0 (the exponent undoes the log). These inverse properties are incredibly useful for simplification: log₃(3⁵) immediately simplifies to 5, and 7^(log₇(20)) immediately simplifies to 20. No calculation needed—they just undo each other! To rewrite 10^3=1000 in logarithmic form, identify the base (10), exponent (3), and result (1000), so log_{10}(1000)=3, where the base stays the same, the result becomes the argument, and the exponent becomes the log value. Choice B correctly converts to log_{10}(1000)=3 using this relationship. A distractor like A swaps the base and argument, but remember, the base is the subscript in log form, matching the exponential base. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same! Evaluating logs using the definition: to find log₂(64), ask 'what power of 2 gives 64?' Think through powers of 2: 2¹ = 2, 2² = 4, 2³ = 8, 2⁴ = 16, 2⁵ = 32, 2⁶ = 64. Found it! 2⁶ = 64, so log₂(64) = 6. This works for any log with a perfect power. If it's not a perfect power (like log₂(10)), you'd need a calculator, but for problems designed for hand calculation, you can find the answer by listing powers of the base until you hit the argument. Question 2
Convert between exponential and logarithmic forms: Rewrite log2(16)=4 as an exponential equation.
- 216=4
- 42=16
- 162=4
- 24=16 (correct answer)
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! To rewrite log₂(16)=4 as an exponential, take base 2 raised to 4 equals 16, so 2^4=16. Choice D correctly converts by making the log base the exponential base, the value the exponent, and the argument the result. A distractor like choice B uses different numbers, but verify that 4^2=16 would be log₄(16)=2, not matching the original. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same! Evaluating logs using the definition: to find log₂(64), ask 'what power of 2 gives 64?' Think through powers of 2: 2¹ = 2, 2² = 4, 2³ = 8, 2⁴ = 16, 2⁵ = 32, 2⁶ = 64. Found it! 2⁶ = 64, so log₂(64) = 6. This works for any log with a perfect power. If it's not a perfect power (like log₂(10)), you'd need a calculator, but for problems designed for hand calculation, you can find the answer by listing powers of the base until you hit the argument.
Question 3
Solve for x: log2(x)=4.
- x=6
- x=8
- x=16 (correct answer)
- x=28
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! To solve log₂(x) = 4, we convert to exponential form: if log₂(x) = 4, then 2⁴ = x. Calculating: 2⁴ = 2 × 2 × 2 × 2 = 16, so x = 16. Choice C correctly identifies that x = 16. Choice A (x = 6) might come from adding 2 + 4. Choice B (x = 8) gives us 2³, not 2⁴. Choice D (x = 2⁸ = 256) reverses the base and exponent positions. Converting between forms: when you have log_b(x) = y, it means b^y = x. So if log₂(x) = 4, then x = 2⁴ = 16. The logarithm tells us the exponent, and we use that exponent to find x.
Question 4
Rewrite the logarithmic equation log5(125)=3 in exponential form using by=x⇔logb(x)=y.
- 35=125
- 1255=3
- 53=125 (correct answer)
- 5125=3
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! To rewrite log₅(125)=3 in exponential form, take the base 5, raise it to the log value 3, to get the argument 125, so 5^3=125. Choice D correctly converts to exponential form by making the log base the exponential base, the log value the exponent, and the argument the result. A distractor like choice C might confuse the numbers, but remember, the log value becomes the exponent, and verify 3^5=243, not 125, so that's incorrect. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same! Evaluating logs using the definition: to find log₂(64), ask 'what power of 2 gives 64?' Think through powers of 2: 2¹ = 2, 2² = 4, 2³ = 8, 2⁴ = 16, 2⁵ = 32, 2⁶ = 64. Found it! 2⁶ = 64, so log₂(64) = 6. This works for any log with a perfect power. If it's not a perfect power (like log₂(10)), you'd need a calculator, but for problems designed for hand calculation, you can find the answer by listing powers of the base until you hit the argument.
Question 5
Rewrite the exponential equation 103=1000 in logarithmic form.
- log1000(10)=3
- log3(10)=1000
- log10(1000)=3 (correct answer)
- log10(3)=1000
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. As inverse operations, logarithms and exponents cancel each other: log_b(bx) = x for any x (the log undoes the exponent), and b^(log_b(x)) = x for x > 0 (the exponent undoes the log). These inverse properties are incredibly useful for simplification: log₃(3⁵) immediately simplifies to 5, and 7^(log₇(20)) immediately simplifies to 20. No calculation needed—they just undo each other! To rewrite 10^3 = 1000 in logarithmic form, identify the base 10, exponent 3, and result 1000, so it becomes log_{10}(1000) = 3. Choice B correctly converts to logarithmic form with the base as 10, argument as 1000, and value as 3. Choice A swaps the argument and value incorrectly, making it log_{10}(3) = 1000, which would imply 10^{1000} = 3, but that's not true. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same! Question 6
If log2(x)=7, find x by rewriting in exponential form.
- 27 (correct answer)
- 14
- log2(7)
- 72
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! Given log_2(x) = 7, rewrite in exponential form as 2^7 = x. Choice B correctly converts to exponential form to find x = 2^7. Choice C swaps the base and exponent, making it 7^2, but that would correspond to a different log equation. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same!
Question 7
Convert between exponential and logarithmic forms: log2(8)=3. Which exponential equation is equivalent?
- 32=8
- 83=2
- 23=8 (correct answer)
- 28=3
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log2(8)=3 because 23=8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! For log2(8)=3, the equivalent exponential is 23=8, where base 2 raised to 3 equals 8. Choice C correctly identifies 23=8 as the equivalent exponential equation. A distractor like B might swap the base and exponent incorrectly, but remember to match the base to the log subscript and the log value to the exponent. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 53=125 has base 5, exponent 3, result 125, so log5(125)=3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same! Evaluating logs using the definition: to find log2(64), ask 'what power of 2 gives 64?' Think through powers of 2: 21=2, 22=4, 23=8, 24=16, 25=32, 26=64. Found it! 26=64, so log2(64)=6. This works for any log with a perfect power. If it's not a perfect power (like log2(10)), you'd need a calculator, but for problems designed for hand calculation, you can find the answer by listing powers of the base until you hit the argument. Question 8
Evaluate log10(1) using the definition logb(x)=y⇔by=x.
- −1
- 10
- 0 (correct answer)
- 1
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! To evaluate \log_{10}(1), find y such that 10^y = 1, and since 10^0=1, y=0. Choice B correctly evaluates to 0 using the definition. A distractor like A (1) might confuse the argument with the value, but remember, the log is the exponent that gives the argument. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same! Evaluating logs using the definition: to find log₂(64), ask 'what power of 2 gives 64?' Think through powers of 2: 2¹ = 2, 2² = 4, 2³ = 8, 2⁴ = 16, 2⁵ = 32, 2⁶ = 64. Found it! 2⁶ = 64, so log₂(64) = 6. This works for any log with a perfect power. If it's not a perfect power (like log₂(10)), you'd need a calculator, but for problems designed for hand calculation, you can find the answer by listing powers of the base until you hit the argument.
Question 9
Solve for x using the inverse relationship: log2(x)=6.
- x=log2(6)
- x=62=36
- x=12
- x=26=64 (correct answer)
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! To solve log₂(x)=6, convert to exponential: 2^6=x, so x=64. Choice B correctly uses the inverse relationship to find x=2^6=64. A distractor like choice C might swap the base and exponent, but remember, the base is raised to the log value to get x. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same! Evaluating logs using the definition: to find log₂(64), ask 'what power of 2 gives 64?' Think through powers of 2: 2¹ = 2, 2² = 4, 2³ = 8, 2⁴ = 16, 2⁵ = 32, 2⁶ = 64. Found it! 2⁶ = 64, so log₂(64) = 6. This works for any log with a perfect power. If it's not a perfect power (like log₂(10)), you'd need a calculator, but for problems designed for hand calculation, you can find the answer by listing powers of the base until you hit the argument.
Question 10
Use the inverse relationship by=x⇔logb(x)=y to evaluate log2(32).
- 4
- 6
- 5 (correct answer)
- 32
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! To evaluate log₂(32), we use the definition by asking what power of 2 equals 32: listing powers, 2^1=2, 2^2=4, 2^3=8, 2^4=16, 2^5=32, so log₂(32)=5. Choice C correctly evaluates using the inverse relationship to find that 2^5=32, so the log is 5. A common distractor like choice D (32) might come from confusing the argument with the result, but remember, the log gives the exponent, not the argument itself. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same! Evaluating logs using the definition: to find log₂(64), ask 'what power of 2 gives 64?' Think through powers of 2: 2¹ = 2, 2² = 4, 2³ = 8, 2⁴ = 16, 2⁵ = 32, 2⁶ = 64. Found it! 2⁶ = 64, so log₂(64) = 6. This works for any log with a perfect power. If it's not a perfect power (like log₂(10)), you'd need a calculator, but for problems designed for hand calculation, you can find the answer by listing powers of the base until you hit the argument.
Question 11
Solve for x: log10(x)=2.
- x=20
- x=210
- x=102 (correct answer)
- x=log(2)
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! To solve log_{10}(x) = 2, rewrite in exponential form as 10^2 = x, so x = 100. Choice C correctly converts to exponential form to get x = 10^2. Choice A might come from confusing the base and mistakenly doing 10*2=20, but that's not the inverse relationship. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same!
Question 12
Convert between exponential and logarithmic forms. Which logarithmic equation is equivalent to 26=64?
- log6(64)=2
- log2(64)=6 (correct answer)
- log64(2)=6
- log2(6)=64
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! For 2^6 = 64, the equivalent logarithmic form is log_2(64) = 6, with base 2, argument 64, and value 6. Choice C correctly converts to logarithmic form to get log_2(64) = 6. Choice A incorrectly sets the base as 6 and the value as 2, which would imply 6^2 = 64, but 6^2 is 36, not 64. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same!
Question 13
Evaluate log2(8) using the definition logb(x)=y⇔by=x.
- 2
- 3 (correct answer)
- 4
- 8
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! To evaluate log₂(8), find the power y such that 2^y=8: 2^3=8, so y=3. Choice B correctly evaluates using the definition to get 3. A distractor like choice D (8) might confuse the argument with the log value, but the log outputs the exponent, not the input. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same! Evaluating logs using the definition: to find log₂(64), ask 'what power of 2 gives 64?' Think through powers of 2: 2¹ = 2, 2² = 4, 2³ = 8, 2⁴ = 16, 2⁵ = 32, 2⁶ = 64. Found it! 2⁶ = 64, so log₂(64) = 6. This works for any log with a perfect power. If it's not a perfect power (like log₂(10)), you'd need a calculator, but for problems designed for hand calculation, you can find the answer by listing powers of the base until you hit the argument.
Question 14
Use the inverse relationship between exponents and logarithms to evaluate log2(32). (Recall: by=x⇔logb(x)=y.)
- 4
- 5 (correct answer)
- 2
- 16
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! To find log₂(32), we need to ask: what power of 2 gives 32? Let's think through powers of 2: 2¹ = 2, 2² = 4, 2³ = 8, 2⁴ = 16, 2⁵ = 32. Perfect! Since 2⁵ = 32, we know that log₂(32) = 5. Choice B correctly identifies that 5 is the exponent needed to make 2 equal 32. Choice A (4) would give us 2⁴ = 16, not 32, while choice C (16) confuses the result with the exponent, and choice D (2) would only give us 2² = 4. Evaluating logs using the definition: to find log₂(64), ask 'what power of 2 gives 64?' Think through powers of 2: 2¹ = 2, 2² = 4, 2³ = 8, 2⁴ = 16, 2⁵ = 32, 2⁶ = 64. Found it! 2⁶ = 64, so log₂(64) = 6. This works for any log with a perfect power.
Question 15
If log10(x)=2, find x by rewriting in exponential form.
- x=20
- x=100 (correct answer)
- x=100
- x=210
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. Given log₁₀(x) = 2, we convert to exponential form: the base 10 stays as base, the log value 2 becomes the exponent, and x is the result. This gives us 10² = x, so x = 100. Choice B correctly identifies that x = 100, since 10² = 100. Choice A incorrectly calculates 10 × 2 = 20 instead of 10², while Choice C gives 10⁰ = 1. When solving logarithmic equations, convert to exponential form first—this transforms the unknown from inside a logarithm to a simple exponential calculation that's much easier to evaluate!
Question 16
Solve for x: log10(x)=2.
- x=102 (correct answer)
- x=20
- x=210
- x=log(2)
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! To solve log_{10}(x) = 2, rewrite in exponential form as 10^2 = x, so x = 100. Choice C correctly converts to exponential form to get x = 10^2. Choice A might come from confusing the base and mistakenly doing 10*2=20, but that's not the inverse relationship. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same!
Question 17
Evaluate log2(32) using the inverse relationship by=x⇔logb(x)=y.
- 32
- 6
- 4
- 5 (correct answer)
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! To evaluate log₂(32), we ask what power of 2 equals 32: since 2^5 = 32, log₂(32) = 5. Choice C correctly evaluates using the inverse relationship to get 5. Choice A might come from mistakenly thinking 2^4 = 32, but 2^4 is actually 16, so that's too low. Evaluating logs using the definition: to find log₂(64), ask 'what power of 2 gives 64?' Think through powers of 2: 2¹ = 2, 2² = 4, 2³ = 8, 2⁴ = 16, 2⁵ = 32, 2⁶ = 64. Found it! 2⁶ = 64, so log₂(64) = 6. This works for any log with a perfect power. If it's not a perfect power (like log₂(10)), you'd need a calculator, but for problems designed for hand calculation, you can find the answer by listing powers of the base until you hit the argument.
Question 18
Convert between forms: Which logarithmic equation is equivalent to the exponential equation 27=128?
- log7(128)=2
- log2(128)=7 (correct answer)
- log128(2)=7
- log2(7)=128
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. For example, log₂(8) = 3 because 2³ = 8—the logarithm (3) is the exponent that makes the base (2) equal the argument (8). This three-part relationship (base, exponent/log, result/argument) is the foundation of everything with logarithms! To convert 2⁷ = 128 to logarithmic form, we identify: base = 2, exponent = 7, result = 128. In logarithmic form: base stays as subscript (2), result becomes argument (128), exponent becomes value (7). So 2⁷ = 128 becomes log₂(128) = 7. Choice D correctly shows this conversion. Choice A incorrectly uses 7 as the base and 2 as the value. Choice B puts 7 as the argument when it should be the value. Choice C makes 128 the base when it should be the argument. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The positions shift but the numbers stay the same!
Question 19
What is the exponential form of log2(x)=7?
- 2x=7
- x2=7
- 27=x (correct answer)
- 72=x
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. The fundamental connection: log_b(x) = y means exactly the same thing as b^y = x. The logarithm log_b(x) asks 'what power of b gives x?', and the answer is that exponent y. Starting with log₂(x) = 7, we convert to exponential form: the base 2 stays as the base, the log value 7 becomes the exponent, and x becomes the result. This gives us 2⁷ = x. Choice C correctly shows this conversion with 2 raised to the power 7 equals x. Choice A incorrectly has x in the exponent position instead of as the result, while Choice B incorrectly uses x as the base. Converting between forms: the subscript base stays the base, the value the log equals becomes the exponent, and the unknown x (which was the argument) becomes the result of the exponential expression!
Question 20
Rewrite the exponential equation 103=1000 in logarithmic form using by=x⇔logb(x)=y.
- log1000(10)=3
- log10(1000)=3 (correct answer)
- log10(3)=1000
- log3(1000)=10
Explanation: This question tests your understanding that logarithms and exponentials are inverse operations—logarithms undo exponentiation and vice versa, just like square roots undo squaring. As inverse operations, logarithms and exponents cancel each other: log_b(bx) = x for any x (the log undoes the exponent), and b^(log_b(x)) = x for x > 0 (the exponent undoes the log). These inverse properties are incredibly useful for simplification: log₃(3⁵) immediately simplifies to 5, and 7^(log₇(20)) immediately simplifies to 20. No calculation needed—they just undo each other! To rewrite 10^3=1000 in logarithmic form, identify the base 10, exponent 3, and result 1000, so it becomes log₁₀(1000)=3. Choice B correctly converts to logarithmic form by placing the base as the subscript, the result as the argument, and the exponent as the log value. A distractor like choice A might swap the base and argument, but gently remember that the base from the exponential stays the base in the log, while the result becomes the input to the log. Converting between forms: identify the three parts—base, exponent, and result. In b^y = x: base is b, exponent is y, result is x. In log_b(x) = y: base is b (subscript), argument is x (inside the log), value is y (what log equals). The exponent in exponential form BECOMES the log value, and the result BECOMES the argument. Example: 5³ = 125 has base 5, exponent 3, result 125, so log₅(125) = 3 has base 5, argument 125, value 3. The positions shift but the numbers stay the same! Evaluating logs using the definition: to find log₂(64), ask 'what power of 2 gives 64?' Think through powers of 2: 2¹ = 2, 2² = 4, 2³ = 8, 2⁴ = 16, 2⁵ = 32, 2⁶ = 64. Found it! 2⁶ = 64, so log₂(64) = 6. This works for any log with a perfect power. If it's not a perfect power (like log₂(10)), you'd need a calculator, but for problems designed for hand calculation, you can find the answer by listing powers of the base until you hit the argument.