Algebra II : Exponents

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #81 : Understanding Exponents

Solve the following:  \(\displaystyle 8^{-2}-2^{-5}\)

Possible Answers:

\(\displaystyle -\frac{1}{16}\)

\(\displaystyle -\frac{3}{32}\)

\(\displaystyle -\frac{3}{64}\)

\(\displaystyle -\frac{1}{32}\)

\(\displaystyle -\frac{1}{64}\)

Correct answer:

\(\displaystyle -\frac{1}{64}\)

Explanation:

In order to simplify this expression, we will need to rewrite the negative exponents.

The negative exponents can be rewritten into fractional form.

\(\displaystyle x^{-b} =\frac{1}{x^b}\)

\(\displaystyle 8^{-2}-2^{-5} = \frac{1}{8^2}-\frac{1}{2^5} = \frac{1}{64}- \frac{1}{32}\)

Convert the second fraction to match the denominator of the first fraction.

\(\displaystyle \frac{1}{64}- \frac{1(2)}{32(2)} = \frac{1}{64}-\frac{2}{64}= -\frac{1}{64}\)

The answer is:  \(\displaystyle -\frac{1}{64}\)

Example Question #82 : Understanding Exponents

Simplify:  \(\displaystyle (\frac{2}{3})^{-3}\)

Possible Answers:

\(\displaystyle \frac{27} {4}\)

\(\displaystyle \frac{1}{2}\)

\(\displaystyle \frac{27}{8}\)

\(\displaystyle \frac{9}{2}\)

\(\displaystyle \frac{9}{8}\)

Correct answer:

\(\displaystyle \frac{27}{8}\)

Explanation:

Rewrite the negative exponent as the reciprocal of the positive power.

The negative exponent can be rewritten into a fraction as follows:

\(\displaystyle x^{-a} =\frac{1}{x^a}\)

\(\displaystyle (\frac{2}{3})^{-3}= \frac{1}{(\frac{2}{3})^3} = \frac{1}{\frac{8}{27}}\)

Simplify the complex fraction.

\(\displaystyle \frac{1}{\frac{8}{27}} = 1\div \frac{8}{27} = 1\times \frac{27}{8}= \frac{27}{8}\)

The answer is:  \(\displaystyle \frac{27}{8}\)

Example Question #81 : Understanding Exponents

Solve:  \(\displaystyle -4^{-3}-2^{-3}\)

Possible Answers:

\(\displaystyle \frac{11}{64}\)

\(\displaystyle -\frac{513}{8}\)

\(\displaystyle -\frac{9}{64}\)

\(\displaystyle -\frac{9}{513}\)

\(\displaystyle -\frac{513}{64}\)

Correct answer:

\(\displaystyle -\frac{9}{64}\)

Explanation:

The negative exponents can be rewritten into a fraction.

\(\displaystyle x^{-a} =\frac{1}{x^a}\)

Rewrite both terms given in the problem.

\(\displaystyle -4^{-3}-2^{-3}=-\frac{1}{4^3}-\frac{1}{2^3} = -\frac{1}{64}-\frac{1}{8}\)

Find the least common denominator of both fractions.

\(\displaystyle -\frac{1}{64}-\frac{1}{8} = -\frac{1}{64}-\frac{1(8)}{8(8)}\)

Simplify the fractions.

\(\displaystyle -\frac{1}{64}-\frac{8}{64}=-\frac{9}{64}\)

The answer is:  \(\displaystyle -\frac{9}{64}\)

Example Question #84 : Understanding Exponents

Solve:  \(\displaystyle -(-8^{-2})+8\)

Possible Answers:

\(\displaystyle 7\frac{1}{8}\)

\(\displaystyle 8\frac{1}{16}\)

\(\displaystyle 4\frac{1}{64}\)

\(\displaystyle 8\frac{1}{64}\)

\(\displaystyle 7\frac{15}{16}\)

Correct answer:

\(\displaystyle 8\frac{1}{64}\)

Explanation:

Simplify the negative exponent as follows:

\(\displaystyle x^{-a} =\frac{1}{x^a}\)

\(\displaystyle 8^{-2} = \frac{1}{8^2} = \frac{1}{64}\)

Rewrite the expression.

\(\displaystyle -(-8^{-2})+8 = -(-\frac{1}{64})+8 = \frac{1}{64}+8\)

The answer is:  \(\displaystyle 8\frac{1}{64}\)

Example Question #85 : Understanding Exponents

Solve:  \(\displaystyle 9^{-2}\times\frac{3}{ 2^{-4}}\)

Possible Answers:

\(\displaystyle \frac{1}{9}\)

\(\displaystyle \frac{1}{432}\)

\(\displaystyle \frac{8}{27}\)

\(\displaystyle \frac{16}{27}\)

\(\displaystyle \frac{3}{16}\)

Correct answer:

\(\displaystyle \frac{16}{27}\)

Explanation:

Change all negative exponents into a fractional form by the following property.

\(\displaystyle x^{-a} =\frac{1}{x^a}\)

\(\displaystyle 9^{-2}\times\frac{3}{ 2^{-4}} = \frac{1}{9^2} \times \frac{3}{\frac{1}{2^4}} = \frac{1}{81} \times \frac{3}{\frac{1}{16}}\)

Simplify the fractions.

\(\displaystyle \frac{1}{81} \times \frac{3}{\frac{1}{16}} = \frac{1}{81} \times 48 = \frac{48}{81}\)

\(\displaystyle \frac{48}{81} =\frac{16 \times 3}{27 \times 3}\)

The answer is:   \(\displaystyle \frac{16}{27}\)

Example Question #81 : Understanding Exponents

Evaluate: \(\displaystyle 7^{-3}\)

Possible Answers:

\(\displaystyle \frac{1}{7^3}\)

\(\displaystyle -21\)

\(\displaystyle 7^3\)

\(\displaystyle -\frac{1}{7^3}\)

\(\displaystyle -7^3\)

Correct answer:

\(\displaystyle \frac{1}{7^3}\)

Explanation:

When dealing with negative exponents, we write \(\displaystyle x^{-a}=\frac{1}{x^a}\). Therefore \(\displaystyle 7^{-3}=\frac{1}{7^3}\).

Example Question #82 : Understanding Exponents

Evaluate: \(\displaystyle (x+5)^{-3}\)

Possible Answers:

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

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

\(\displaystyle \frac{5^3}{x}\)

\(\displaystyle \frac{5^3}{(x+5)^3}\)

\(\displaystyle \frac{x}{5^3}\)

Correct answer:

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

Explanation:

When dealing with negative exponents, we write \(\displaystyle x^{-a}=\frac{1}{x^a}\). Therefore \(\displaystyle (x+5)^{-3}=\frac{1}{(x+5)^3}\)

Example Question #83 : Understanding Exponents

Evaluate: \(\displaystyle (\frac{2}{3})^{-2}\)

Possible Answers:

\(\displaystyle -\frac{9}{4}\)

\(\displaystyle -\frac{4}{9}\)

\(\displaystyle 36\)

\(\displaystyle \frac{4}{9}\)

\(\displaystyle \frac{9}{4}\)

Correct answer:

\(\displaystyle \frac{9}{4}\)

Explanation:

When dealing with negative exponents, we write \(\displaystyle x^{-a}=\frac{1}{x^a}\). Therefore \(\displaystyle (\frac{2}{3})^{-2}=\frac{1}{(\frac{2}{3})^2}=\frac{1}{\frac{4}{9}}=\frac{9}{4}\).

Example Question #84 : Understanding Exponents

Simplify: \(\displaystyle (\frac{x}{6})^{-3}\)

Possible Answers:

\(\displaystyle -\frac{256}{x^3}\)

\(\displaystyle \frac{256}{x^3}\)

\(\displaystyle \frac{x^3}{256}\)

\(\displaystyle -\frac{x^3}{256}\)

\(\displaystyle \frac{6}{x^3}\)

Correct answer:

\(\displaystyle \frac{256}{x^3}\)

Explanation:

When dealing with negative exponents, we write \(\displaystyle x^{-a}=\frac{1}{x^a}\). Therefore \(\displaystyle (\frac{x}{6})^{-3}=\frac{1}{(\frac{x}{6})^3}=\frac{1}{\frac{x^3}{256}}=\frac{256}{x^3}\).

Example Question #85 : Understanding Exponents

Evaluate: \(\displaystyle 3^{-4}\)

Possible Answers:

\(\displaystyle -12\)

\(\displaystyle 81\)

\(\displaystyle -\frac{1}{81}\)

\(\displaystyle \frac{1}{81}\)

\(\displaystyle -81\)

Correct answer:

\(\displaystyle \frac{1}{81}\)

Explanation:

When dealing with exponents, we convert as such: \(\displaystyle x^{-a}=\frac{1}{x^a}\). Therefore, \(\displaystyle 3^{-4}=\frac{1}{3^4}=\frac{1}{81}\).

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