Algebra II : Fractional Exponents

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #1 : Exponents

Simplify the expression:

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

Possible Answers:

\(\displaystyle 64\)

\(\displaystyle 256\)

\(\displaystyle 1024\)

\(\displaystyle 16\)

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.

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

 

Example Question #2 : Exponents

Convert the exponent to radical notation.

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

Possible Answers:

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

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

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

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

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 #41 : Basic Single Variable Algebra

Simplify:

\(\displaystyle [x^{1/2}]^{7/3}\)

Possible Answers:

\(\displaystyle x^{8/6}\)

\(\displaystyle x^{7/6}\)

\(\displaystyle x^{17/6}\)

\(\displaystyle x^{5/2}\)

\(\displaystyle x^{4/3}\)

Correct answer:

\(\displaystyle x^{7/6}\)

Explanation:

\(\displaystyle [x^{m}]^{n}=x^{m\times n}\)

\(\displaystyle x^{1/2\times 7/3}=x^{7/6}\)

Example Question #2 : Fractional Exponents

Write the product of \(\displaystyle \small a^\frac{3}{4}*a^\frac{3}{8}*a^\frac{5}{2}\) in radical form

Possible Answers:

\(\displaystyle \small \sqrt[2]{a^5}\)

\(\displaystyle \small \sqrt[29]{a^8}\)

\(\displaystyle \small \sqrt[a]{8^2^9}\)

\(\displaystyle \small \sqrt[a]{29^8}\)

\(\displaystyle \small \sqrt[8]{a^2^9}\)

Correct answer:

\(\displaystyle \small \sqrt[8]{a^2^9}\)

Explanation:

This problem relies on the key knowledge that \(\displaystyle \small x^\frac{a}{b}=\sqrt[b]{x^a}\) and that the multiplying terms with exponents requires adding the exponents. Therefore, we can rewrite the expression thusly:

\(\displaystyle \small a^\frac{3}{4}*a^\frac{3}{8}*a^\frac{5}{2}=a^{\frac{3}{4}+\frac{3}{8}+\frac{5}{2}}=a^{\frac{29}{8}}=\sqrt[8]{a^{29}}\)

Therefore, \(\displaystyle \small \sqrt[8]{a^{29}}\) is our final answer.

Example Question #3 : Fractional Exponents

Evaluate the following expression:

\(\displaystyle \bigg(\frac{27}{125}\bigg)^{\frac{1}{3}}\)

Possible Answers:

\(\displaystyle \sqrt{\frac{27}{125}}\)

\(\displaystyle \frac{3}{\sqrt{25}}\)

\(\displaystyle \frac{3}{25}\)

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

\(\displaystyle \frac{9}{5}\)

Correct answer:

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

Explanation:

\(\displaystyle \bigg(\frac{27}{125}\bigg)^{\frac{1}{3}} = \frac{27^{\frac{1}{3}}}{125^{\frac{1}{3}}}=\frac{3}{5}\)

or

\(\displaystyle \bigg(\frac{27}{125}\bigg)^{\frac{1}{3}}= \sqrt[3]{\frac{27}{125}}=\frac{\sqrt[3]{27}}{\sqrt[3]{125}}=\frac{3}{5}\)

Example Question #2 : Fractional Exponents

Simplify:

\(\displaystyle \frac{x^{\frac{1}{2}}y^2}{x^{\frac{-3}{2}}y^4}\)

Possible Answers:

\(\displaystyle \frac{x^2}{y^2}\)

\(\displaystyle \frac{1}{x^2y^2}\)

\(\displaystyle \frac{y^2}{x^2}\)

\(\displaystyle x^2y^2\)

Correct answer:

\(\displaystyle \frac{x^2}{y^2}\)

Explanation:

Keep in mind that when you are dividing exponents with the same base, you will want to subtract the exponent found in the denominator from the exponent found in the numerator.

To find the exponent for \(\displaystyle x\), subtract the denominator's exponent from the numerator's exponent.

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

To find the exponent for \(\displaystyle y\), subtract the denominator's exponent from the numerator's exponent.

\(\displaystyle 2-4=-2\)

Since the exponent is negative, you will want to put the \(\displaystyle y\) in the denominator in order to make it positive.

So then,

\(\displaystyle \frac{x^{\frac{1}{2}}y^2}{x^{\frac{-3}{2}}y^4}=\frac{x^2}{y^2}\)

Example Question #1 : Fractional Exponents

Find the value of \(\displaystyle 9^{\frac{3}{2}}\).

Possible Answers:

\(\displaystyle 27\)

\(\displaystyle 729\)

\(\displaystyle 3\)

\(\displaystyle 81\)

Correct answer:

\(\displaystyle 27\)

Explanation:

When you have a number or value with a fractional exponent, 

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

or

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

So then,

\(\displaystyle 9^{\frac{3}{2}}=\sqrt[2]{9^3}=\sqrt{729}=27\)

\(\displaystyle 9^{\frac{3}{2}}=(\sqrt9)^3=3^3=27\)

Example Question #2 : Fractional Exponents

Find the value of \(\displaystyle 64^{\frac{4}{3}}\)

Possible Answers:

\(\displaystyle 256\)

\(\displaystyle 512\)

\(\displaystyle 4096\)

\(\displaystyle 1024\)

Correct answer:

\(\displaystyle 256\)

Explanation:

When you have a number or value with a fractional exponent, 

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

or

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

So then,

\(\displaystyle 64^{\frac{4}{3}}=\sqrt[3]{64^4}=\sqrt[3]{2^{24}}=2^8=256\)

Example Question #3 : Fractional Exponents

Simplify:

\(\displaystyle (27t^3)^\frac{5}{3}\)

Possible Answers:

\(\displaystyle 243t^5\)

\(\displaystyle 243t^{\frac{8}{3}}\)

\(\displaystyle 81t^5\)

\(\displaystyle 27t^5\)

Correct answer:

\(\displaystyle 243t^5\)

Explanation:

When exponents are raised to another exponent, you will need to multiply the exponents together.

When you have a number or value with a fractional exponent, 

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

or

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

So,

\(\displaystyle 27^{\frac{5}{3}}=\sqrt[3]{27^5}=\sqrt[3]{3^{15}}=3^5=243\)

\(\displaystyle (t^3)^{\frac{5}{3}}=t^{3\times\frac{5}{3}}=t^{\frac{15}{3}}=t^5\)

\(\displaystyle (27t^3)^\frac{5}{3}=243t^5\)

 

Example Question #1 : Fractional Exponents

Simplify:  \(\displaystyle 25^{\frac{3}{2}}\)

Possible Answers:

\(\displaystyle 125\)

\(\displaystyle 50\)

\(\displaystyle 90\)

\(\displaystyle 45\)

\(\displaystyle 75\)

Correct answer:

\(\displaystyle 125\)

Explanation:

An option to solve this is to split up the fraction.  Rewrite the fractional exponent as follows:

\(\displaystyle 25^{\frac{3}{2}} = (25^{\frac{1}{2}})^3\)

A value to its half power is the square root of that value.

\(\displaystyle 25^{\frac{1}{2}} = \sqrt{25}=5\)

Substitute this value back into \(\displaystyle (25^{\frac{1}{2}})^3\).

\(\displaystyle (25^{\frac{1}{2}})^3 = (5)^3 = 5\times 5\times 5 = 125\)

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