SAT Math : Basic Squaring / Square Roots

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #973 : Sat Mathematics

Simplify: 

\(\displaystyle -2\sqrt{5}(7\sqrt{3}+3\sqrt{10})\)

Possible Answers:

\(\displaystyle -14\sqrt{5}-5\sqrt{2}\)

\(\displaystyle -14\sqrt{5}+30\sqrt{2}\)

\(\displaystyle -14\sqrt{15}-30\sqrt{2}\)

\(\displaystyle 14\sqrt{5}-6\sqrt{2}\)

\(\displaystyle -19\sqrt{10}\)

Correct answer:

\(\displaystyle -14\sqrt{15}-30\sqrt{2}\)

Explanation:

To simplify the problem, just distribute the radical to each term in the parentheses. 

\(\displaystyle \\-2\sqrt{5}(7\sqrt{3}+3\sqrt{10})\\=-14\sqrt{15}-6\sqrt{50}\)

\(\displaystyle \\-14\sqrt{15}-6\sqrt{50}\\=-14\sqrt{15}-6*5\sqrt{2}\\=-14\sqrt{15}-30\sqrt{2}\)

Example Question #974 : Sat Mathematics

Simplify: 

\(\displaystyle (\sqrt{2}+\sqrt{7})(\sqrt{27}+\sqrt{12})\)

Possible Answers:

\(\displaystyle 5\sqrt{6}+2\sqrt{21}+3\sqrt{2}\)

\(\displaystyle 3\sqrt{3}+2\sqrt{21}\)

\(\displaystyle 5\sqrt{6}+5\sqrt{21}\)

\(\displaystyle 2\sqrt{5}+5\sqrt{2}+3\sqrt{6}\)

\(\displaystyle 3\sqrt{6}+2\sqrt{2}+2\sqrt{3}+3\sqrt{7}\)

Correct answer:

\(\displaystyle 5\sqrt{6}+5\sqrt{21}\)

Explanation:

 \(\displaystyle (\sqrt{2}+\sqrt{7})(\sqrt{27}+\sqrt{12})\) 

Let's simplify the right parentheses.

\(\displaystyle (\sqrt{27}+\sqrt{12})=(3\sqrt{{3}}+2\sqrt{3})=5\sqrt{3}\) 

Now we can distribute the radical to each term in the parentheses.

\(\displaystyle 5\sqrt{3}(\sqrt{2}+\sqrt{7})=5\sqrt{6}+5\sqrt{21}\)

 

Example Question #3 : Square Roots And Operations

If \sqrt{x}=3^2\(\displaystyle \sqrt{x}=3^2\) what is x\(\displaystyle x\)?

Possible Answers:

9\(\displaystyle 9\)

81\(\displaystyle 81\)

729\(\displaystyle 729\)

27\(\displaystyle 27\)

3\(\displaystyle 3\)

Correct answer:

81\(\displaystyle 81\)

Explanation:

Square both sides:

x = (32)2 = 92 = 81

Example Question #21 : Basic Squaring / Square Roots

Simplify in radical form:

\(\displaystyle \sqrt{507}+\sqrt{12}\)

Possible Answers:

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

\(\displaystyle 11\sqrt{6}\)

\(\displaystyle 15\sqrt{3}\)

\(\displaystyle 26\sqrt{3}\)

\(\displaystyle \sqrt{519}\)

Correct answer:

\(\displaystyle 15\sqrt{3}\)

Explanation:

To simplify, break down each square root into its component factors:

\(\displaystyle \sqrt{507}+\sqrt{12}\)

\(\displaystyle \sqrt{169\cdot 3}+\sqrt{4\cdot 3}\)

\(\displaystyle \sqrt{13\cdot13\cdot3}\:+\sqrt{2\cdot 2\cdot 3}\)

You can remove pairs of factors and bring them outside the square root sign. At this point, since each term shares \(\displaystyle \sqrt3\), you can add them together to yield the final answer:

\(\displaystyle 13\sqrt{3}+2\sqrt{3}=15\sqrt{3}\)

Example Question #1 : How To Add Square Roots

Simplify: \(\displaystyle \frac{2\sqrt{3}}{\sqrt{2}}+\frac{4\sqrt{2}}{\sqrt{3}}\)

 

Possible Answers:

\(\displaystyle \frac{7\sqrt{6}}{3}\)

\(\displaystyle 2\sqrt{6}-4\sqrt{2}\)

\(\displaystyle 2\sqrt{6}\)

\(\displaystyle 4\sqrt{3}+\sqrt{2}\)

None of the other answers

Correct answer:

\(\displaystyle \frac{7\sqrt{6}}{3}\)

Explanation:

Take each fraction separately first:

(2√3)/(√2) = [(2√3)/(√2)] * [(√2)/(√2)] = (2 * √3 * √2)/(√2 * √2) = (2 * √6)/2 = √6

Similarly:

(4√2)/(√3) = [(4√2)/(√3)] * [(√3)/(√3)] = (4√6)/3 = (4/3)√6

Now, add them together:

√6 + (4/3)√6 = (3/3)√6 + (4/3)√6 = (7/3)√6

Example Question #12 : Square Roots And Operations

Simplify the following expression: \(\displaystyle \sqrt{60}+\sqrt{40}+\sqrt{10}\)

Possible Answers:

\(\displaystyle 2\sqrt{15}+2\sqrt{20}\)

\(\displaystyle 5\sqrt{25}\)

\(\displaystyle 25\)

\(\displaystyle 4\sqrt{15}+5\sqrt{5}\)

\(\displaystyle 2\sqrt{15}+3\sqrt{10}\)

Correct answer:

\(\displaystyle 2\sqrt{15}+3\sqrt{10}\)

Explanation:

Begin by factoring out each of the radicals:

\(\displaystyle \sqrt{60}+\sqrt{40}+\sqrt{10}=\sqrt{4*15}+\sqrt{4*10}+\sqrt{10}\)

For the first two radicals, you can factor out a \(\displaystyle \sqrt{4}\) or \(\displaystyle 2\):

\(\displaystyle 2\sqrt{15}+2\sqrt{10}+\sqrt{10}\)

The other root values cannot be simply broken down. Now, combine the factors with \(\displaystyle \sqrt{10}\):

\(\displaystyle 2\sqrt{15}+2\sqrt{10}+\sqrt{10}=2\sqrt{15}+3\sqrt{10}\)

This is your simplest form.

Example Question #4 : How To Add Square Roots

Solve for \(\displaystyle x\).

Note, \(\displaystyle x\ge0\):

\(\displaystyle 15\sqrt{x}-10=4\sqrt{x}+4\)

Possible Answers:

\(\displaystyle \frac{841}{14}\)

\(\displaystyle \frac{841}{5}\)

\(\displaystyle 81\)

\(\displaystyle \frac{196}{121}\)

\(\displaystyle \frac{196}{11}\)

Correct answer:

\(\displaystyle \frac{196}{121}\)

Explanation:

Begin by getting your \(\displaystyle x\) terms onto the left side of the equation and your numeric values onto the right side of the equation:

\(\displaystyle 15\sqrt{x}-4\sqrt{x}=4+10\)

Next, you can combine your radicals. You do this merely by subtracting their respective coefficients:

\(\displaystyle 11\sqrt{x}=14\)

Now, square both sides:

\(\displaystyle (11\sqrt{x})^2=(14)^2\)

\(\displaystyle (11)^2(\sqrt{x})^2=(14)^2\)

\(\displaystyle 121x=196\)

Solve by dividing both sides by \(\displaystyle 121\):

\(\displaystyle x=\frac{196}{121}\)

Example Question #1 : How To Subtract Square Roots

Evaluate: \(\displaystyle \sqrt{108}-\sqrt{81}\)

Possible Answers:

\(\displaystyle 6\sqrt{3}-9\)

\(\displaystyle 4\sqrt{27}-\sqrt{9}\)

\(\displaystyle 24\sqrt{3}-81\)

None of the available answers

\(\displaystyle 24\sqrt{3}-9\)

Correct answer:

\(\displaystyle 6\sqrt{3}-9\)

Explanation:

Let us factor 108 and 81

\(\displaystyle 108=2\times 54= 2\times 2\times 27= 2^2\times 3\times 9= 2^2\times 3^2\times 3\)

\(\displaystyle 81=9\times 9=9^2\)

\(\displaystyle \sqrt{108}-\sqrt{81}=6\sqrt{3}-9\)

Example Question #1 : How To Divide Square Roots

(√27 + √12) / √3 is equal to

Possible Answers:

5/√3

(6√3)/√3

18

5

√3

Correct answer:

5

Explanation:

√27 is the same as 3√3, while √12 is the same as 2√3.

3√3 + 2√3 = 5√3

(5√3)/(√3) = 5

Example Question #2 : How To Divide Square Roots

Simplify: \(\displaystyle \frac{\sqrt{210}}{\sqrt{6}}\)

Possible Answers:

\(\displaystyle \sqrt{13}\)

\(\displaystyle 6\)

\(\displaystyle \sqrt{35}\)

\(\displaystyle 5\sqrt{7}\)

\(\displaystyle 7\sqrt{5}\)

Correct answer:

\(\displaystyle \sqrt{35}\)

Explanation:

When dividing square roots, we divide the numbers inside the radical. Simplify if necessary.

\(\displaystyle \frac{\sqrt{210}}{\sqrt{6}}=\frac{\sqrt{35}*\sqrt{6}}{\sqrt{6}}=\sqrt{35}\)

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