Algebra II : Radicals

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #31 : Adding And Subtracting Radicals

\(\displaystyle -\sqrt{24}+6\sqrt{40}+2\sqrt{80}\)

Possible Answers:

\(\displaystyle -12+6\sqrt{40}+2\sqrt{80}\)

\(\displaystyle 18\sqrt{4}\)

\(\displaystyle 18\sqrt{8}\)

\(\displaystyle -2\sqrt{6}+12\sqrt{10}+8\sqrt{5}\)

\(\displaystyle -12+12\sqrt{10}+8\sqrt{5}\)

Correct answer:

\(\displaystyle -2\sqrt{6}+12\sqrt{10}+8\sqrt{5}\)

Explanation:

To add or subtract radicals, they must be the same root and have the same number under the radical before combining them. Look for perfect squares that divide into the number under the radicals because those can be simplified.

\(\displaystyle -\sqrt{24}+6\sqrt{40}+2\sqrt{80}\)

\(\displaystyle -\sqrt{4\cdot 6}+6\sqrt{4\cdot 10}+2\sqrt{16\cdot 5}\)

Take the square roots of each of the perfect squares in these radicals and bring it out of the radical. It will multiply to any coefficient in front of that radical

\(\displaystyle -2\sqrt{6}+6\cdot 2\sqrt{10}+2\cdot 4\sqrt{5}\)

\(\displaystyle -2\sqrt{6}+12\sqrt{10}+8\sqrt{5}\)

Example Question #41 : Adding And Subtracting Radicals

\(\displaystyle 4\sqrt{169}+7\sqrt{52}+5\sqrt{325}\)

Possible Answers:

\(\displaystyle 52+39\sqrt{13}\)

\(\displaystyle 25\sqrt{13}\)

\(\displaystyle 12\sqrt{13}\)

\(\displaystyle 91\sqrt{13}\)

\(\displaystyle 16\sqrt{13}\)

Correct answer:

\(\displaystyle 52+39\sqrt{13}\)

Explanation:

To add or subtract radicals, they must be the same root and have the same number under the radical before combining them. Look for perfect squares that divide into the number under the radicals because those can be simplified.

\(\displaystyle 4\sqrt{169}+7\sqrt{52}+5\sqrt{325}\)

\(\displaystyle 4\cdot 13+7\sqrt{4\cdot 13}+5\sqrt{25\cdot 13}\)

Take the square roots of each of the perfect squares in these radicals and bring it out of the radical. It will multiply to any coefficient in front of that radical

\(\displaystyle 52+7\cdot 2\sqrt{13}+5\cdot 5\sqrt{13}\)

\(\displaystyle 52+14\sqrt{13}+25\sqrt{13}\)

\(\displaystyle 52+39\sqrt{13}\)

Example Question #81 : Simplifying Radicals

\(\displaystyle 9\sqrt{14}-3\sqrt{126}+5\sqrt{896}\)

Possible Answers:

\(\displaystyle 58\sqrt{14}\)

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

\(\displaystyle 40\sqrt{14}\)

\(\displaystyle 16\sqrt{14}\)

\(\displaystyle 28\sqrt{14}\)

Correct answer:

\(\displaystyle 40\sqrt{14}\)

Explanation:

To add or subtract radicals, they must be the same root and have the same number under the radical before combining them. Look for perfect squares that divide into the number under the radicals because those can be simplified.

\(\displaystyle 9\sqrt{14}-3\sqrt{126}+5\sqrt{896}\)

\(\displaystyle 9\sqrt{14}-3\sqrt{9\cdot 14}+5\sqrt{64\cdot 14}\)

Take the square roots of each of the perfect squares in these radicals and bring it out of the radical. It will multiply to any coefficient in front of that radical

\(\displaystyle 9\sqrt{14}-3\cdot 3\sqrt{14}+5\cdot 8\sqrt{14}\)

\(\displaystyle 9\sqrt{14}-9\sqrt{14}+40\sqrt{14}\)

\(\displaystyle 40\sqrt{14}\)

Example Question #4081 : Algebra Ii

\(\displaystyle 10\sqrt{44}+5\sqrt{99}-7\sqrt{275}\)

Possible Answers:

\(\displaystyle 8\sqrt{11}\)

\(\displaystyle \sqrt{11}\)

\(\displaystyle -90\sqrt{11}\)

\(\displaystyle 0\)

\(\displaystyle -21\sqrt{11}\)

Correct answer:

\(\displaystyle 0\)

Explanation:

To add or subtract radicals, they must be the same root and have the same number under the radical before combining them. Look for perfect squares that divide into the number under the radicals because those can be simplified.

\(\displaystyle 10\sqrt{44}+5\sqrt{99}-7\sqrt{275}\)

\(\displaystyle 10\sqrt{4\cdot 11}+5\sqrt{9\cdot 11}-7\sqrt{25\cdot 11}\)

Take the square roots of each of the perfect squares in these radicals and bring it out of the radical. It will multiply to any coefficient in front of that radical

\(\displaystyle 10\cdot 2\sqrt{11}+5\cdot 3\sqrt{11}-7\cdot 5\sqrt{11}\)

\(\displaystyle 20\sqrt{11}+15\sqrt{11}-35\sqrt{11}\)

\(\displaystyle 0\)

Example Question #44 : Adding And Subtracting Radicals

Add the following radicals, if possible:  \(\displaystyle \sqrt2+\sqrt3+\sqrt{12}+\sqrt{24}\)

Possible Answers:

\(\displaystyle \sqrt{41}\)

\(\displaystyle \sqrt2+3\sqrt3+2\sqrt6\)

\(\displaystyle \textup{The problem cannot be simplified any further.}\)

\(\displaystyle 2\sqrt2+4\sqrt3\)

\(\displaystyle 2\sqrt2+\sqrt3+2\sqrt6\)

Correct answer:

\(\displaystyle \sqrt2+3\sqrt3+2\sqrt6\)

Explanation:

Rewrite \(\displaystyle \sqrt{12}\) and \(\displaystyle \sqrt{24}\) by their factors.  The first two terms are already in their simplest forms.

\(\displaystyle \sqrt{12} = \sqrt{4} \cdot \sqrt{3} = 2\sqrt3\)

\(\displaystyle \sqrt{24} = \sqrt{4}\cdot \sqrt{6} = 2\sqrt6\)

Rewrite the expression.

\(\displaystyle \sqrt2+\sqrt3+\sqrt{12}+\sqrt{24}= \sqrt2+\sqrt3+ 2\sqrt3+2\sqrt6\)

Combine like-terms.

The answer is:  \(\displaystyle \sqrt2+3\sqrt3+2\sqrt6\)

Example Question #41 : Adding And Subtracting Radicals

Add the radicals:  \(\displaystyle \sqrt{20} +\sqrt{45}\)

Possible Answers:

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

\(\displaystyle 5\sqrt5\)

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

\(\displaystyle \textup{The square roots are already simplified.}\)

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

Correct answer:

\(\displaystyle 5\sqrt5\)

Explanation:

Simplify the square roots by writing them as a common factor of perfect squares.

\(\displaystyle \sqrt{20} +\sqrt{45} = \sqrt4 \cdot \sqrt5+ \sqrt9 \cdot \sqrt5\)

Simplify the perfect squares.

\(\displaystyle \sqrt4 \cdot \sqrt5+ \sqrt9 \cdot \sqrt5 = 2\sqrt5+3\sqrt5\)

Combine like-terms.

The answer is:  \(\displaystyle 5\sqrt5\)

Example Question #91 : Simplifying Radicals

\(\displaystyle 3\sqrt{175}-4\sqrt{252}+2\sqrt{112}\)

Possible Answers:

\(\displaystyle \sqrt{7}\)

\(\displaystyle 7\sqrt{13}\)

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

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

\(\displaystyle 15\sqrt{7}\)

Correct answer:

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

Explanation:

To add or subtract radicals, they must be the same root and have the same number under the radical before combining them. Look for perfect squares that divide into the number under the radicals because those can be simplified.

\(\displaystyle 3\sqrt{175}-4\sqrt{252}+2\sqrt{112}\)

\(\displaystyle 3\sqrt{25\cdot 7}-4\sqrt{36\cdot 7}+2\sqrt{16\cdot 7}\)

Take the square roots of each of the perfect squares in these radicals and bring it out of the radical. It will multiply to any coefficient in front of that radical

\(\displaystyle 3\cdot 5\sqrt{7}-4\cdot 6\sqrt{7}+2\cdot 4\sqrt{7}\)

\(\displaystyle 15\sqrt{7}-24\sqrt{7}+8\sqrt{7}\)

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

Example Question #47 : Adding And Subtracting Radicals

\(\displaystyle 3\sqrt{48}-\sqrt{72}+5\sqrt{75}\)

Possible Answers:

\(\displaystyle 10\srt5-3\sqrt{13}\)

\(\displaystyle 27\sqrt{3}-6\sqrt{2}\)

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

\(\displaystyle 6\sqrt2-12\)

\(\displaystyle 37\sqrt{3}-6\sqrt{2}\)

Correct answer:

\(\displaystyle 37\sqrt{3}-6\sqrt{2}\)

Explanation:

To add or subtract radicals, they must be the same root and have the same number under the radical before combining them. Look for perfect squares that divide into the number under the radicals because those can be simplified.

\(\displaystyle 3\sqrt{48}-\sqrt{72}+5\sqrt{75}\)

\(\displaystyle 3\sqrt{16\cdot 3}-\sqrt{36\cdot 2}+5\sqrt{25\cdot 3}\)

Take the square roots of each of the perfect squares in these radicals and bring it out of the radical. It will multiply to any coefficient in front of that radical

\(\displaystyle 3\cdot 4\sqrt{3}-6\sqrt{2}+5\cdot 5\sqrt{3}\)

\(\displaystyle 12\sqrt{3}-6\sqrt{2}+25\sqrt{3}\)

Remember, only radicals with the same number can be combined

\(\displaystyle 37\sqrt{3}-6\sqrt{2}\)

This is the final answer.

Example Question #48 : Adding And Subtracting Radicals

\(\displaystyle 2\sqrt{125}-\sqrt{320}+4\sqrt{180}\)

Possible Answers:

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

\(\displaystyle 12\sqrt{5}\)

\(\displaystyle \sqrt{5}\)

\(\displaystyle 20\sqrt{5}\)

\(\displaystyle 26\sqrt{5}\)

Correct answer:

\(\displaystyle 26\sqrt{5}\)

Explanation:

To add or subtract radicals, they must be the same root and have the same number under the radical before combining them. Look for perfect squares that divide into the number under the radicals because those can be simplified.

\(\displaystyle 2\sqrt{125}-\sqrt{320}+4\sqrt{180}\)

\(\displaystyle 2\sqrt{25\cdot 5}-\sqrt{64\cdot 5}+4\sqrt{36\cdot 5}\)

Take the square roots of each of the perfect squares in these radicals and bring it out of the radical. It will multiply to any coefficient in front of that radical

\(\displaystyle 2\cdot 5\sqrt{5}-8\sqrt{5}+4\cdot 6\sqrt{5}\)

\(\displaystyle 10\sqrt{5}-8\sqrt{5}+24\sqrt{5}\)

\(\displaystyle 26\sqrt{5}\)

Example Question #91 : Simplifying Radicals

Add the radicals, if possible:  \(\displaystyle \sqrt{50}+\sqrt{125}\)

Possible Answers:

\(\displaystyle 5\sqrt{2}+5\sqrt5\)

\(\displaystyle 10\sqrt5\)

\(\displaystyle 5\sqrt{2}+10\sqrt5\)

\(\displaystyle \textup{The radicals cannot be simplified any further.}\)

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

Correct answer:

\(\displaystyle 5\sqrt{2}+5\sqrt5\)

Explanation:

Use common factors to simplify both radicals.

\(\displaystyle \sqrt{50}+\sqrt{125} = \sqrt{25\times 2}+\sqrt{25\times 5}\)

\(\displaystyle = \sqrt{25}\cdot \sqrt{2}+\sqrt{25}\cdot \sqrt{5}\)

Simplify the square roots.

The answer is:  \(\displaystyle 5\sqrt{2}+5\sqrt5\)

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