SAT Math : Arithmetic

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #7 : How To Simplify Square Roots

Simplify (\frac{16}{81})^{1/4}\(\displaystyle (\frac{16}{81})^{1/4}\).

Possible Answers:

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

\frac{8}{81}\(\displaystyle \frac{8}{81}\)

\frac{4}{81}\(\displaystyle \frac{4}{81}\)

\frac{2}{81}\(\displaystyle \frac{2}{81}\)

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

Correct answer:

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

Explanation:

(\frac{16}{81})^{1/4}\(\displaystyle (\frac{16}{81})^{1/4}\)

\(\displaystyle =\)\frac{16^{1/4}}{81^{1/4}}\(\displaystyle \frac{16^{1/4}}{81^{1/4}}\)

\(\displaystyle =\)\frac{(2\cdot 2\cdot 2\cdot 2)^{1/4}}{(3\cdot 3\cdot 3\cdot 3)^{1/4}}\(\displaystyle \frac{(2\cdot 2\cdot 2\cdot 2)^{1/4}}{(3\cdot 3\cdot 3\cdot 3)^{1/4}}\)

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

Example Question #1 : How To Simplify Square Roots

Simplfy the following radical \(\displaystyle \sqrt{20x^{2}}\).

Possible Answers:

\(\displaystyle 2x\sqrt{5}\)

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

\(\displaystyle 2x\sqrt{10}\)

\(\displaystyle 4\sqrt{5x}\)

Correct answer:

\(\displaystyle 2x\sqrt{5}\)

Explanation:

You can rewrite the equation as \(\displaystyle \sqrt{20x^2}=(x)\sqrt{5} \cdot \sqrt{4}\).

This simplifies to \(\displaystyle 2x\sqrt{5}\).

Example Question #1 : How To Simplify Square Roots

Which of the following is equal to \(\displaystyle \sqrt{75}\) ?

Possible Answers:

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

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

\(\displaystyle 9\)

\(\displaystyle 7.5\sqrt{10}\)

Correct answer:

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

Explanation:

√75 can be broken down to √25 * √3. Which simplifies to 5√3.

Example Question #2 : How To Simplify Square Roots

Simplify \sqrt{a^{3}b^{4}c^{5}}\(\displaystyle \sqrt{a^{3}b^{4}c^{5}}\).

Possible Answers:

a^{2}b^{2}c^{2}\sqrt{bc}\(\displaystyle a^{2}b^{2}c^{2}\sqrt{bc}\)

a^{2}b^{2}c\sqrt{ab}\(\displaystyle a^{2}b^{2}c\sqrt{ab}\)

a^{2}bc^{2}\sqrt{ac}\(\displaystyle a^{2}bc^{2}\sqrt{ac}\)

ab^{2}c^{2}\sqrt{ac}\(\displaystyle ab^{2}c^{2}\sqrt{ac}\)

a^{2}bc\sqrt{bc}\(\displaystyle a^{2}bc\sqrt{bc}\)

Correct answer:

ab^{2}c^{2}\sqrt{ac}\(\displaystyle ab^{2}c^{2}\sqrt{ac}\)

Explanation:

Rewrite what is under the radical in terms of perfect squares:

x^{2}=x\cdot x\(\displaystyle x^{2}=x\cdot x\)

x^{4}=x^{2}\cdot x^{2}\(\displaystyle x^{4}=x^{2}\cdot x^{2}\)

x^{6}=x^{3}\cdot x^{3}\(\displaystyle x^{6}=x^{3}\cdot x^{3}\)

Therefore, \sqrt{a^{3}b^{4}c^{5}}= \sqrt{a^{2}a^{1}b^{4}c^{4}c^{1}}=ab^{2}c^{2}\sqrt{ac}\(\displaystyle \sqrt{a^{3}b^{4}c^{5}}= \sqrt{a^{2}a^{1}b^{4}c^{4}c^{1}}=ab^{2}c^{2}\sqrt{ac}\).

Example Question #3 : How To Simplify Square Roots

What is \(\displaystyle \sqrt{50}\)?

Possible Answers:

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

\(\displaystyle 10\)

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

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

\(\displaystyle 5\)

Correct answer:

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

Explanation:

We know that 25 is a factor of 50. The square root of 25 is 5. That leaves \(\displaystyle \sqrt{2}\) which can not be simplified further.

Example Question #4 : How To Simplify Square Roots

Which of the following is equivalent to \frac{x + \sqrt{3}}{3x + \sqrt{2}}\(\displaystyle \frac{x + \sqrt{3}}{3x + \sqrt{2}}\)?

Possible Answers:

\frac{3x^{2} + 3x\sqrt{2} + x\sqrt{3} +\sqrt{6}}{9x^{2} - 2}\(\displaystyle \frac{3x^{2} + 3x\sqrt{2} + x\sqrt{3} +\sqrt{6}}{9x^{2} - 2}\)

\frac{3x^{2} - \sqrt{6}}{9x^{2} + 2}\(\displaystyle \frac{3x^{2} - \sqrt{6}}{9x^{2} + 2}\)

\frac{4x + \sqrt{5}}{3x + 2}\(\displaystyle \frac{4x + \sqrt{5}}{3x + 2}\)

\frac{3x^{2} -x \sqrt{2} + 3x\sqrt{3} - \sqrt{6}}{9x^{2} - 2}\(\displaystyle \frac{3x^{2} -x \sqrt{2} + 3x\sqrt{3} - \sqrt{6}}{9x^{2} - 2}\)

\frac{3x^{2} + \sqrt{6}}{3x - 2}\(\displaystyle \frac{3x^{2} + \sqrt{6}}{3x - 2}\)

Correct answer:

\frac{3x^{2} -x \sqrt{2} + 3x\sqrt{3} - \sqrt{6}}{9x^{2} - 2}\(\displaystyle \frac{3x^{2} -x \sqrt{2} + 3x\sqrt{3} - \sqrt{6}}{9x^{2} - 2}\)

Explanation:

Multiply by the conjugate and the use the formula for the difference of two squares:

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

\(\displaystyle =\) \frac{x + \sqrt{3}}{3x + \sqrt{2}}\cdot \frac{3x - \sqrt{2}}{3x - \sqrt{2}}\(\displaystyle \frac{x + \sqrt{3}}{3x + \sqrt{2}}\cdot \frac{3x - \sqrt{2}}{3x - \sqrt{2}}\)

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

\(\displaystyle =\) \frac{3x^{2} -x \sqrt{2} + 3x\sqrt{3} - \sqrt{6}}{9x^{2} - 2}\(\displaystyle \frac{3x^{2} -x \sqrt{2} + 3x\sqrt{3} - \sqrt{6}}{9x^{2} - 2}\)

Example Question #5 : How To Simplify Square Roots

Which of the following is the most simplified form of:

\(\displaystyle \sqrt{468}\)

 

Possible Answers:

\(\displaystyle 4\sqrt{29}\)

\(\displaystyle 17\sqrt{2}\)

\(\displaystyle 6\sqrt{13}\)

\(\displaystyle 2\sqrt{117}\)

\(\displaystyle \sqrt{468}\)

Correct answer:

\(\displaystyle 6\sqrt{13}\)

Explanation:

First find all of the prime factors of \(\displaystyle 468\)

\(\displaystyle 468=6\ast78=6\ast6\ast13=2\ast3\ast2\ast3\ast13\)

So \(\displaystyle \sqrt{468}=\sqrt{2\ast2\ast3\ast3\ast13}=2\ast3\sqrt{13}=6\sqrt{13}\)

Example Question #6 : How To Simplify Square Roots

What is \(\displaystyle \sqrt{432}\) equal to?

Possible Answers:

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

\(\displaystyle 144\sqrt{3}\)

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

\(\displaystyle 12\sqrt{3}\)

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

Correct answer:

\(\displaystyle 12\sqrt{3}\)

Explanation:

\(\displaystyle \sqrt{432}\)

 

1. We know that \(\displaystyle 432=(144)(3)\), which we can separate under the square root:

\(\displaystyle \sqrt{144\cdot 3}\)

 

2. 144 can be taken out since it is a perfect square: \(\displaystyle 12\cdot12=144\). This leaves us with:

\(\displaystyle 12\sqrt{3}\)

This cannot be simplified any further.

Example Question #1001 : Sat Mathematics

Simplify:  \(\displaystyle \sqrt{240}\)

Possible Answers:

\(\displaystyle 15\sqrt2\)

\(\displaystyle 12\sqrt{4}\)

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

\(\displaystyle 3\sqrt{27}\)

\(\displaystyle 5\sqrt{13}\)

Correct answer:

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

Explanation:

Write out the common square factors of the number inside the square root.

\(\displaystyle \sqrt{240}= \sqrt{4\times 60}= 2\sqrt{60}\)

Continue to find the common factors for 60.

\(\displaystyle 2\sqrt{60} = 2\sqrt{4\times 15} = 2(2\sqrt{15}) = 4\sqrt{15}\)

Since there are no square factors for \(\displaystyle \sqrt{15}\), the answer is in its simplified form.  It might not have been easy to see that 16 was a common factor of 240.

The answer is: \(\displaystyle 4\sqrt{15}\)

Example Question #1002 : Sat Mathematics

Simplify:

\(\displaystyle \sqrt{48}\)

Possible Answers:

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

\(\displaystyle 2\sqrt{24}\)

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

\(\displaystyle 6\)

None of the given answers. 

Correct answer:

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

Explanation:

To simplify, we want to find some factors of \(\displaystyle 48\) where at least one of the factors is a perfect square. 

In this case, \(\displaystyle 16\) and \(\displaystyle 3\) are factors of \(\displaystyle 48\), and \(\displaystyle 16\) is a perfect square. 

We can simplify by saying:

\(\displaystyle \sqrt{48} = \sqrt{16\cdot 3} = \sqrt{4^2 \cdot 3} = 4\sqrt{3}\)

We could also recognize that two factors of \(\displaystyle 48\) are \(\displaystyle 4\) and \(\displaystyle 12\). We could approach this way by saying:

\(\displaystyle \sqrt{48}=\sqrt{4 \cdot 12} = \sqrt {2^2 \cdot 12} = 2\sqrt{12}\)

But we wouldn't stop there. That's because \(\displaystyle 12\) can be further factored:

\(\displaystyle 2\sqrt{12} = 2\sqrt{4 \cdot 3} = 2\sqrt{2^2 \cdot 3} = 2\cdot 2 \sqrt{3} = 4\sqrt{3}\)

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