Algebra II : Simplifying Radicals

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #4001 : Algebra Ii

Simplify.

\(\displaystyle \sqrt{6}\)

Possible Answers:

\(\displaystyle 1\)

\(\displaystyle 6\)

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

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

\(\displaystyle \sqrt{6}\)

Correct answer:

\(\displaystyle \sqrt{6}\)

Explanation:

When simplifying radicals, you want to factor the radicand and look for square numbers.

\(\displaystyle \sqrt{6}=\sqrt{2\cdot 3}\) 

Both the \(\displaystyle 2\) and \(\displaystyle 3\) are not perfect squares, so the answer is just \(\displaystyle \sqrt{6}\)

Example Question #11 : Simplifying Radicals

Simplify.

\(\displaystyle \sqrt{36}\)

Possible Answers:

\(\displaystyle 6\)

\(\displaystyle \sqrt{6}\)

\(\displaystyle \sqrt{36}\)

\(\displaystyle 1\)

\(\displaystyle 5\)

Correct answer:

\(\displaystyle 6\)

Explanation:

When simplifying radicals, you want to factor the radicand and look for square numbers.

\(\displaystyle \sqrt{36}=\sqrt{9\cdot 4}=3\cdot 2=6\)

 \(\displaystyle 36\) is a perfect square so the answer is just \(\displaystyle 6\)

Example Question #4003 : Algebra Ii

Simplify.

\(\displaystyle \sqrt{729}\)

Possible Answers:

\(\displaystyle 9\)

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

\(\displaystyle \sqrt{729}\)

\(\displaystyle 3\)

\(\displaystyle 27\)

Correct answer:

\(\displaystyle 27\)

Explanation:

When simplifying radicals, you want to factor the radicand and look for square numbers.

\(\displaystyle \sqrt{729}=\sqrt{9\cdot81}=3\cdot9=27\)

If you aren't sure whether \(\displaystyle 729\) can be factored, use divisibility rules. Since it's odd and not ending in \(\displaystyle 5\), lets check if \(\displaystyle 3\) is a possible factor. To know if a number is factorable by \(\displaystyle 3\), you add the sum of the individual numbers in that number.

\(\displaystyle 729=7+2+9=18\)

Since \(\displaystyle 18\) is divisible by \(\displaystyle 3\), just divide \(\displaystyle 729\) by \(\displaystyle 3\) and continue doing this. You should do this \(\displaystyle 5\) more times and see that \(\displaystyle 729= 3\cdot3\cdot3\cdot3\cdot3\cdot3\)

Since \(\displaystyle 9\) is a perfect square, or \(\displaystyle 3^2\) we can simplify the radical as follows.

\(\displaystyle \sqrt{729}=\sqrt{3\cdot3\cdot3\cdot3\cdot3\cdot3}=\sqrt{9\cdot9\cdot9}= 3\cdot3\cdot3=27\)

Example Question #101 : Radicals

Simplify.

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

Possible Answers:

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

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

\(\displaystyle \sqrt{7}\)

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

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

Correct answer:

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

Explanation:

When simplifying radicals, you want to factor the radicand and look for square numbers.

\(\displaystyle \sqrt{8}=\sqrt{2\cdot 4}\)

 Since \(\displaystyle 4\) is a perfect square but \(\displaystyle 2\) is not, we can write it like this:

\(\displaystyle \sqrt{8}=\sqrt{2\cdot4}=2\sqrt{2}\) 

Remember, the other factor that's not a perfect square is left in the radicand and the square root of the perfect square is outside the radical. 

Example Question #11 : Factoring Radicals

Simplify.

\(\displaystyle \sqrt{600}\)

Possible Answers:

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

\(\displaystyle \sqrt{600}\)

\(\displaystyle 10\sqrt{6}\)

\(\displaystyle 60\sqrt{10}\)

\(\displaystyle 6\sqrt{10}\)

Correct answer:

\(\displaystyle 10\sqrt{6}\)

Explanation:

When simplifying radicals, you want to factor the radicand and look for square numbers.

\(\displaystyle \sqrt{600}=\sqrt{100\cdot6}\) 

Since \(\displaystyle 100\) is a perfect square but \(\displaystyle 6\) is not, we can write it as follows:

\(\displaystyle \sqrt{600}=\sqrt{100\cdot6}=10\sqrt{6}\) 

Remember, the other factor that's not a perfect square is left in the radicand and the square root of the perfect square is outside the radical. 

Example Question #4006 : Algebra Ii

Simplify.

\(\displaystyle \sqrt{242}\)

Possible Answers:

\(\displaystyle 2\sqrt{11}\)

\(\displaystyle \sqrt{34}\)

\(\displaystyle \sqrt{242}\)

\(\displaystyle \sqrt{78}\)

\(\displaystyle 11\sqrt{2}\)

Correct answer:

\(\displaystyle 11\sqrt{2}\)

Explanation:

When simplifying radicals, you want to factor the radicand and look for square numbers.

\(\displaystyle \sqrt{242}=\sqrt{2\cdot 121}\) 

Since \(\displaystyle 121\) is a perfect square but \(\displaystyle 2\) is not, we can write it like this:

\(\displaystyle \sqrt{242}=\sqrt{2\cdot 121}=11\sqrt{2}\) 

Remember, the other factor that's not a perfect square is left in the radicand and the square root of the perfect square is outside the radical. 

If you didn't know \(\displaystyle 121\) was a perfect square, there's a divisibility rule for \(\displaystyle 11\). If the ones digit and hundreds digit adds up to the tens value, then it's divisibile by \(\displaystyle 11\)\(\displaystyle 1+1=2\) so \(\displaystyle 121\) is divisible by \(\displaystyle 11\) and its other factor is also \(\displaystyle 11\). It's best to memorize perfect squares up to \(\displaystyle 20.\)

Example Question #11 : Factoring Radicals

Simplify.

\(\displaystyle \sqrt{\frac{1}{4}}\)

Possible Answers:

\(\displaystyle 0\)

\(\displaystyle 4\)

\(\displaystyle \sqrt{\frac{1}{4}}\)

\(\displaystyle \frac{1}{2}\)

\(\displaystyle 2\)

Correct answer:

\(\displaystyle \frac{1}{2}\)

Explanation:

When simplifying radicals, you want to factor the radicand and look for square numbers.

\(\displaystyle \sqrt{\frac{1}{4}}=\sqrt{\frac{1}{2}\cdot \frac{1}{2}}\) 

It's essentially the same factor so the answer is \(\displaystyle \frac{1}{2}\).

Example Question #111 : Radicals

Simplify.

\(\displaystyle \sqrt{(x^2+4x+4)}\)

Possible Answers:

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

\(\displaystyle x+2\)

\(\displaystyle x\)

\(\displaystyle \sqrt{x^2+4x+4}\)

\(\displaystyle 4x\)

Correct answer:

\(\displaystyle x+2\)

Explanation:

Let's see if this quadratic can be broken down. Remember, we need to find two terms that are factors of the c term that add up to the b term.

It turns out that \(\displaystyle x^2+4x+4 = (x+2)^2\).

The second power and square root cancel out leaving you with just \(\displaystyle x+2\).

Example Question #12 : Simplifying Radicals

Simplify.

\(\displaystyle \sqrt{4x^2+8x+4}\)

Possible Answers:

\(\displaystyle 2(x+1)\)

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

\(\displaystyle 2\)

\(\displaystyle 2x\)

\(\displaystyle \sqrt{4x^2+8x+4}\)

Correct answer:

\(\displaystyle 2(x+1)\)

Explanation:

Let's factor a \(\displaystyle 4\) out first since they divide evenly with all of the terms.

We get \(\displaystyle 4(x^2+2x+1)\)

Let's see if this quadratic can be broken down. Remember, we need to find two terms that are factors of the c term that add up to the b term.

It turns out that \(\displaystyle x^2+2x+1 = (x+1)^2\).

We have \(\displaystyle 2\) perfect squares so the final answer is \(\displaystyle 2(x+1)\)

Example Question #15 : Simplifying Radicals

Simplify.

\(\displaystyle \sqrt{36x^2y^4}\)

Possible Answers:

\(\displaystyle 6xy^2\)

\(\displaystyle 36x\sqrt{y^4}\)

\(\displaystyle \sqrt{36x^2y^4}\)

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

\(\displaystyle 6x\sqrt{y^4}\)

Correct answer:

\(\displaystyle 6xy^2\)

Explanation:

When simplifying radicals, you want to factor the radicand and look for perfect squares.

\(\displaystyle \sqrt{36x^2y^4}=\sqrt{9\cdot 4\cdot x\cdot x\cdot y^2\cdot y^2}=3\cdot2\cdotx\cdoty^2=6xy^2\)

 \(\displaystyle 36, x^2, y^4\) are perfect squares so the answer is \(\displaystyle 6xy^2\)

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