SAT Math : Simplifying Square Roots

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #41 : How To Simplify Square Roots

Simplify: \(\displaystyle \sqrt{448}\)

Possible Answers:

\(\displaystyle 8\sqrt{7}\)

\(\displaystyle 7\sqrt{8}\)

\(\displaystyle 12\sqrt{7}\)

\(\displaystyle 64\sqrt{7}\)

\(\displaystyle 16\sqrt{7}\)

Correct answer:

\(\displaystyle 8\sqrt{7}\)

Explanation:

To simplify square roots, we need to factor out perfect squares. In this case, it's \(\displaystyle 64\).

\(\displaystyle \sqrt{448}=\sqrt{64}*\sqrt{7}=8\sqrt{7}\)

Example Question #42 : How To Simplify Square Roots

Simplify: \(\displaystyle \sqrt{x^5}\)

Possible Answers:

\(\displaystyle x^4\sqrt{x}\)

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

\(\displaystyle x^2\sqrt{x}\)

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

\(\displaystyle x\sqrt{x}\)

Correct answer:

\(\displaystyle x^2\sqrt{x}\)

Explanation:

To simplify the radical, we should factor out perfect squares. 

\(\displaystyle \sqrt{x^5}=\sqrt{x^2}*\sqrt{x^2}*\sqrt{x}=x*x\sqrt{x}=x^2\sqrt{x}\)

Example Question #43 : How To Simplify Square Roots

Simplify: \(\displaystyle \sqrt{x^7y^3}\)

Possible Answers:

\(\displaystyle x^6y^2\sqrt{xy}\)

\(\displaystyle x^3y\sqrt{xy}\)

\(\displaystyle xy\sqrt{x^3y^2}\)

\(\displaystyle x^2y\sqrt{x^3y}\)

\(\displaystyle x^3\sqrt{xy^3}\)

Correct answer:

\(\displaystyle x^3y\sqrt{xy}\)

Explanation:

To simplify the square roots, we need to factor out the perfect squares.

\(\displaystyle \sqrt{x^7y^3}=\sqrt{x^2}*\sqrt{x^2}*\sqrt{x^2}*\sqrt{y^2}*\sqrt{xy}=x^3y\sqrt{xy}\)

Example Question #44 : How To Simplify Square Roots

Simplify: \(\displaystyle \sqrt{4^5*5^4}\)

Possible Answers:

\(\displaystyle 2^4*5^4\sqrt{2}\)

\(\displaystyle 2^4*5^2\sqrt{10}\)

\(\displaystyle 2^3*5^2\sqrt{32}\)

\(\displaystyle 2^5*5^2\)

\(\displaystyle 2^5*5^2\sqrt{5}\)

Correct answer:

\(\displaystyle 2^5*5^2\)

Explanation:

To simplify the square roots, we need to factor out perfect squares. 

\(\displaystyle \sqrt{4^5*5^4}=\sqrt{4^2}*\sqrt{4^2}*\sqrt{4}*\sqrt{5^2}*\sqrt{5^2}=4*4*2*5*5\)

We can combine to have two different bases. Remember \(\displaystyle 4=2^2\).

\(\displaystyle 4*4*2*5*5=2^2*2^2*2*5^2=2^5*5^2\)

Example Question #44 : How To Simplify Square Roots

Simplify: \(\displaystyle \sqrt{(-8)^8}\)

Possible Answers:

\(\displaystyle -8^4\)

\(\displaystyle 8^{16}\)

\(\displaystyle 8^4\)

\(\displaystyle -8^6\)

\(\displaystyle 8^8\)

Correct answer:

\(\displaystyle 8^4\)

Explanation:

To simplify the square root, we need to determine the value of the exponent and then simplify the radical.

\(\displaystyle \sqrt{(-8)^8}=\sqrt{8^8}\) Now let's find perfect squares.

\(\displaystyle \sqrt{8^8}=\sqrt{8^4}*\sqrt{8^4}=8^2*8^2=8^4\)

Example Question #45 : How To Simplify Square Roots

Simplify: \(\displaystyle \sqrt{(-9)^{10}}\)

Possible Answers:

\(\displaystyle 9^{10}\)

\(\displaystyle -9^{-5}\)

\(\displaystyle 9^{-5}\)

\(\displaystyle -9^5\)

\(\displaystyle 9^5\)

Correct answer:

\(\displaystyle 9^5\)

Explanation:

To simplify the square root, we need to determine the value of the exponent and then simplify the radical.

\(\displaystyle \sqrt{(-9)^{10}}=\sqrt{9^{10}}\) Now let's find perfect squares.

\(\displaystyle \sqrt{9^{10}}=\sqrt{9^5}*\sqrt{9^5}=9^{2}*9^2*\sqrt{9}*\sqrt{9}=9^4*9=9^5\)

Example Question #46 : How To Simplify Square Roots

Simplify: \(\displaystyle \frac{\sqrt{48}}{2}\)

Possible Answers:

\(\displaystyle \frac{4\sqrt{3}}{3}\)

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

\(\displaystyle \sqrt{24}\)

\(\displaystyle 4\sqrt{3}\)

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

Correct answer:

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

Explanation:

To simplify the radical, we need to find perfect squares. Then if possible, we can reduc the fraction.

\(\displaystyle \sqrt{48}=\sqrt{16}*\sqrt{3}=4\sqrt{3}\)

\(\displaystyle \frac{4\sqrt{3}}{2}=2\sqrt{3}\)

Example Question #141 : Arithmetic

Simplify: \(\displaystyle \frac{\sqrt{(-8)^4}}{12}\)

Possible Answers:

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

\(\displaystyle \frac{8}{3}\)

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

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

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

Correct answer:

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

Explanation:

To simplify the radical, let's deal with the parentheses first and apply the exponents. Reduce if necessary.

\(\displaystyle \sqrt{(-8)^4}=\sqrt{8^4}=8^2=64\)

\(\displaystyle \frac{64}{12}=\frac{64\div4}{12\div4}=\frac{16}{3}\)

Example Question #41 : How To Simplify Square Roots

Simplify: \(\displaystyle \frac{5}{\sqrt{3}+2}\)

Possible Answers:

\(\displaystyle 10-5\sqrt{3}\)

\(\displaystyle 5\sqrt{3}-10\)

\(\displaystyle \frac{5\sqrt{3}-10}{7}\)

\(\displaystyle {5\sqrt{3}+10}\)

\(\displaystyle \frac{5\sqrt{3}-2}{5}\)

Correct answer:

\(\displaystyle 10-5\sqrt{3}\)

Explanation:

To eliminate a radical expression, we need to multiply top and bottom by the conjugate which is opposite the sign in the expression. Then simplify if necessary.

\(\displaystyle \frac{5}{\sqrt{3}+2}=\frac{5}{\sqrt{3}+2}*\frac{\sqrt{3}-2}{\sqrt{3}-2}=\frac{5\sqrt{3}-10}{3-4}=-(5\sqrt{3}-10)=10-5\sqrt{3}\)

Example Question #50 : How To Simplify Square Roots

Simplify: 

\(\displaystyle \sqrt{6^5*8^3}\)

Possible Answers:

\(\displaystyle 576\sqrt{3}\)

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

\(\displaystyle 6^4*2^6\sqrt{48}\)

\(\displaystyle 576\sqrt{6}\)

\(\displaystyle 1152\sqrt{3}\)

Correct answer:

\(\displaystyle 1152\sqrt{3}\)

Explanation:

To simplify square roots, we need to find perfect squares to factor out.

\(\displaystyle \sqrt{6^5*8^3}=\sqrt{6^2}*\sqrt{6^2}*\sqrt{8^2}*\sqrt{48}\) 

We can also simplify\(\displaystyle \sqrt{48}=\sqrt{16}\times \sqrt{3}=4\sqrt{3}\)

Thus,

\(\displaystyle 6^2\cdot 8\cdot4\sqrt{3}\)

We can compute the numbers outside to get a final answer of \(\displaystyle 1152\sqrt{3}\).

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