High School Math : Understanding Exponents

Study concepts, example questions & explanations for High School Math

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Example Questions

Example Question #1 : Understanding Negative Exponents

Which of the following is equivalent to \displaystyle 3^{-2} ? 

Possible Answers:

\displaystyle \frac{1}{6}

\displaystyle -6

\displaystyle \frac{1}{9}

\displaystyle 1

\displaystyle -9

Correct answer:

\displaystyle \frac{1}{9}

Explanation:

By definition, 

\displaystyle b^{-x} = \frac{1}{b^{x}}.

In our problem, \displaystyle b = 3 and \displaystyle x = 2

Then, we have \displaystyle \frac{1}{3^{2}} = \frac{1}{9}.

Example Question #1 : Exponents

Solve for \displaystyle x:

\displaystyle (x+5)^{-3} = -1

Possible Answers:

\displaystyle -5

\displaystyle -1

\displaystyle -6

\displaystyle -3

\displaystyle -4

Correct answer:

\displaystyle -6

Explanation:

Raise both sides of the equation to the inverse power of \displaystyle -3 to cancel the exponent on the left hand side of the equation.

\displaystyle \rightarrow ((x+5)^{-3})^{-\frac{1}{3}} = (-1)^{-\frac{1}{3}}

\displaystyle \rightarrow x+5 = -1

Subtract \displaystyle 5 from both sides:

\displaystyle \rightarrow (x+5) - 5 = (-1)-5

\displaystyle \rightarrow x = -6

Example Question #1 : Understanding Fractional Exponents

Convert the exponent to radical notation.

\displaystyle x^{\frac{3}{7}}

Possible Answers:

\displaystyle \small \small \sqrt[7]{x^3}

\displaystyle \small \small \sqrt[3]{x^7}

\displaystyle \small \frac{1}{x^4}

\displaystyle \small \frac{x^3}{x^7}

Correct answer:

\displaystyle \small \small \sqrt[7]{x^3}

Explanation:

Remember that exponents in the denominator refer to the root of the term, while exponents in the numerator can be treated normally.

\displaystyle x^{\frac{a}{b}}=\sqrt[b]{x^a}

\displaystyle x^{\frac{3}{7}}=\sqrt[7]{x^3}

Example Question #1 : Exponents

Which of the following is equivalent to \displaystyle 64^{\frac{1}{2}} ?

Possible Answers:

\displaystyle \frac{1}{32}

\displaystyle 32

\displaystyle 8

\displaystyle 16

\displaystyle -32

Correct answer:

\displaystyle 8

Explanation:

By definition, a number raised to the \displaystyle \frac{1}{2} power is the same as the square root of that number. 

Since the square root of 64 is 8, 8 is our solution. 

Example Question #1 : Fractional Exponents

Simplify the expression:

\displaystyle \small (16^{\frac{1}{2}})(256^{\frac{3}{4}})

Possible Answers:

\displaystyle 256

\displaystyle 16

\displaystyle 64

\displaystyle 1024

Correct answer:

\displaystyle 256

Explanation:

Remember that fraction exponents are the same as radicals.

\displaystyle \small 16^{\frac{1}{2}}=\sqrt{16}=4

\displaystyle 256^{\frac{3}{4}}=\sqrt[4]{256^3}=64

A shortcut would be to express the terms as exponents and look for opportunities to cancel.

\displaystyle 16^{\frac{1}{2}}=(4^2)^{\frac{1}{2}}=4

\displaystyle \small 256^{\frac{3}{4}}=(4^4)^{\frac{3}{4}}=4^3=64

Either method, we then need to multiply to two terms.

\displaystyle \small (4)(64)=256

 

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