Algebra II : Algebra II

Study concepts, example questions & explanations for Algebra II

varsity tutors app store varsity tutors android store

Example Questions

Example Question #41 : Negative Exponents

Evaluate \(\displaystyle 21^{-2}\)

Possible Answers:

\(\displaystyle 441\)

\(\displaystyle -42\)

\(\displaystyle -441\)

\(\displaystyle \frac{1}{441}\)

\(\displaystyle -\frac{1}{441}\)

Correct answer:

\(\displaystyle \frac{1}{441}\)

Explanation:

When expressing negative exponents, we rewrite as such: 

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

in which \(\displaystyle a\) is the positive exponent raising base \(\displaystyle x\).

\(\displaystyle 21^{-2}=\frac{1}{21^2}=\frac{1}{441}\)

Example Question #50 : Understanding Exponents

Evaluate \(\displaystyle -4^{-4}\)

Possible Answers:

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

\(\displaystyle -\frac{1}{256}\)

\(\displaystyle 16\)

\(\displaystyle \frac{1}{256}\)

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

Correct answer:

\(\displaystyle -\frac{1}{256}\)

Explanation:

When expressing negative exponents, we rewrite as such: 

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

in which \(\displaystyle a\) is the positive exponent raising base \(\displaystyle x\).

\(\displaystyle -4^{-4}=-\frac{1}{4^4}=-\frac{1}{256}\)

Example Question #51 : Negative Exponents

Evaluate \(\displaystyle (-5)^{-4}\)

Possible Answers:

\(\displaystyle -\frac{1}{625}\)

\(\displaystyle \frac{1}{20}\)

\(\displaystyle -20\)

\(\displaystyle 20\)

\(\displaystyle \frac{1}{625}\)

Correct answer:

\(\displaystyle \frac{1}{625}\)

Explanation:

When expressing negative exponents, we rewrite as such: 

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

in which \(\displaystyle a\) is the positive exponent raising base \(\displaystyle x\).

\(\displaystyle (-5)^{-4}=\frac{1}{(-5)^4}=\frac{1}{625}\)

Example Question #51 : Negative Exponents

Evaluate \(\displaystyle \frac{1}{2}^{-3}\)

Possible Answers:

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

\(\displaystyle -\frac{1}{6}\)

\(\displaystyle -8\)

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

\(\displaystyle 8\)

Correct answer:

\(\displaystyle 8\)

Explanation:

When expressing negative exponents, we rewrite as such: 

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

in which \(\displaystyle a\) is the positive exponent raising base \(\displaystyle x\).

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

Example Question #53 : Understanding Exponents

Evaluate \(\displaystyle \frac{1}{6}^{-\frac{1}{2}}\)

Possible Answers:

\(\displaystyle \frac{\sqrt{6}}{6}\)

\(\displaystyle \sqrt{6}\)

\(\displaystyle 6\)

\(\displaystyle -\sqrt{6}\)

\(\displaystyle \frac{1}{36}\)

Correct answer:

\(\displaystyle \sqrt{6}\)

Explanation:

When dealing with fractional exponents, we rewrite as such: 

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

in which \(\displaystyle b\) is the index of the radical and \(\displaystyle a\) is the exponent raising base \(\displaystyle a\)

When expressing negative exponents, we rewrite as such: 

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

in which \(\displaystyle a\) is the positive exponent raising base \(\displaystyle x\).

\(\displaystyle \frac{1}{6}^{-\frac{1}{2}}=\frac{1}{(\sqrt\frac{1}{6})}=\frac{1}{\frac{1}{\sqrt{6}}}=\sqrt{6}\)

Example Question #51 : Exponents

Evaluate \(\displaystyle 12^{-\frac{1}{2}}\)

Possible Answers:

\(\displaystyle \frac{\sqrt{3}}{6}\)

\(\displaystyle \frac{1}{12}\)

\(\displaystyle 2\sqrt{3}\)

\(\displaystyle 6\sqrt{3}\)

\(\displaystyle \frac{\sqrt{3}}{2}\)

Correct answer:

\(\displaystyle \frac{\sqrt{3}}{6}\)

Explanation:

When dealing with fractional exponents, we rewrite as such: 

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

in which \(\displaystyle b\) is the index of the radical and \(\displaystyle a\) is the exponent raising base \(\displaystyle a\)

When expressing negative exponents, we rewrite as such: 

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

in which \(\displaystyle a\) is the positive exponent raising base \(\displaystyle x\).

\(\displaystyle 12^{-\frac{1}{2}}=\frac{1}{(\sqrt{12})}=\frac{1}{2{\sqrt{3}}}=\frac{\sqrt{3}}{6}\) 

Remember when getting rid of radicals, just multiply top and bottom by that radical.

Example Question #55 : Understanding Exponents

Evaluate \(\displaystyle 48^{-\frac{2}{3}}\)

Possible Answers:

\(\displaystyle \frac{\sqrt[3]{6}}{24}\)

\(\displaystyle \frac{\sqrt{3}}{24}\)

\(\displaystyle \frac{\sqrt{3}}{6}\)

\(\displaystyle \frac{\sqrt[3]{36}}{16}\)

\(\displaystyle \frac{\sqrt{6}}{16}\)

Correct answer:

\(\displaystyle \frac{\sqrt[3]{6}}{24}\)

Explanation:

When dealing with fractional exponents, we rewrite as such: 

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

in which \(\displaystyle b\) is the index of the radical and \(\displaystyle a\) is the exponent raising base \(\displaystyle a\)

When expressing negative exponents, we rewrite as such: 

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

in which \(\displaystyle a\) is the positive exponent raising base \(\displaystyle x\).

\(\displaystyle 48^{-\frac{2}{3}}=\frac{1}{\sqrt[3]{48^2}}=\frac{1}{\sqrt[3]{2304}}\) 

Let's find a perfect cube which is 

\(\displaystyle 64 =(4^3)\).

\(\displaystyle \frac{1}{\sqrt[3]{2304}}=\frac{1}{\sqrt[3]{64}*\sqrt[3]{36}}=\frac{1}{4\sqrt[3]{36}}\) 

To simplify, we need to multiply top and bottom by an appropriate cubic root. We know \(\displaystyle 36=6^2\) so if we multiply top and bottom by \(\displaystyle \sqrt[3]{6}\) we will get an integer in the denominator.

\(\displaystyle \frac{1}{4\sqrt[3]{36}}*\frac{\sqrt[3]{6}}{\sqrt[3]{6}}=\frac{\sqrt[3]{6}}{4*6}=\frac{\sqrt[3]{6}}{24}\)

Example Question #56 : Understanding Exponents

Evaluate \(\displaystyle 12^{-\frac{3}{4}}\)

Possible Answers:

\(\displaystyle \frac{\sqrt[4]{12}}{8}\)

\(\displaystyle \frac{\sqrt[4]{12}}{12}\)

\(\displaystyle \frac{\sqrt[3]{36}}{16}\)

\(\displaystyle \frac{\sqrt{6}}{12}\)

\(\displaystyle \frac{\sqrt[3]{12}}{12}\)

Correct answer:

\(\displaystyle \frac{\sqrt[4]{12}}{12}\)

Explanation:

When dealing with fractional exponents, we rewrite as such: 

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

in which \(\displaystyle b\) is the index of the radical and \(\displaystyle a\) is the exponent raising base \(\displaystyle a\)

When expressing negative exponents, we rewrite as such: 

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

in which \(\displaystyle a\) is the positive exponent raising base \(\displaystyle x\).

\(\displaystyle 12^{-\frac{3}{4}}=\frac{1}{\sqrt[4]{12^3}}=\frac{1}{\sqrt[4]{1728}}\) 

Let's find a perfect fourth power which is 

\(\displaystyle 16 = (2^4)\).

\(\displaystyle \frac{1}{\sqrt[4]{1728}}=\frac{1}{\sqrt[4]{16}*\sqrt[4]{108}}=\frac{1}{2\sqrt[4]{108}}\) 

To simplify, we need to multiply top and bottom by an appropriate fourth root. We know \(\displaystyle 108=3^3*2^2\).

We need to complete the numbers to the fourth power. It we multiply top and bottom by \(\displaystyle \sqrt[4]{3*2^2}=\sqrt[4]{12}\) we will get an integer in the denominator.

\(\displaystyle \frac{1}{2\sqrt[4]{108}}*\frac{\sqrt[4]{12}}{\sqrt[4]{12}}=\frac{\sqrt[4]{12}}{2*6}=\frac{\sqrt[4]{12}}{12}\)

Example Question #51 : Exponents

Simplify \(\displaystyle (4x^{2}y^{-6})(2x^{-7}y^{^3})\).

Possible Answers:

\(\displaystyle 8x^{5}y^{3}\)

\(\displaystyle \frac{1}{8x^{14}y^{18}}\)

\(\displaystyle \frac{8}{x^{5}y^{3}}\)

\(\displaystyle \frac{1}{8x^{5}y^{3}}\)

\(\displaystyle \frac{8}{x^{14}y^{18}}\)

Correct answer:

\(\displaystyle \frac{8}{x^{5}y^{3}}\)

Explanation:

First multiply the like terms, remembering that when multiplying terms that have exponents, you add the exponents.

\(\displaystyle (4x^{2}y^{-6})(2x^{-7}y^{3})=(4\cdot 2)(x^{2}\cdot x^{-7})(y^{-6}\cdot y^{3})\)

\(\displaystyle =8x^{2-7}y^{-6+3}\)

\(\displaystyle =8x^{-5}y^{-3}\)

Negative exponents indicate that the term should be in the denominator, so the final answer is:

\(\displaystyle \frac{8}{x^{5}y^{3}}\)

Example Question #51 : Understanding Exponents

Simplify:  \(\displaystyle 6^{-2}+3^{-2}\)

Possible Answers:

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

\(\displaystyle \frac{5}{36}\)

\(\displaystyle \sqrt{6}+\sqrt{3}\)

\(\displaystyle \frac{5}{18}\)

\(\displaystyle -3\)

Correct answer:

\(\displaystyle \frac{5}{36}\)

Explanation:

Convert each negative exponent into fractional form.

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

\(\displaystyle 6^{-2}+3^{-2}=\frac{1}{6^2}+\frac{1}{3^2}\)

Simplify the denominators.

\(\displaystyle \frac{1}{36}+\frac{1}{9}\)

Convert the second fraction with a common denominator of 36.

\(\displaystyle \frac{1}{36}+\frac{4}{36}= \frac{5}{36}\)

The answer is:  \(\displaystyle \frac{5}{36}\)

Learning Tools by Varsity Tutors