Algebra II : Simplifying Radicals

Study concepts, example questions & explanations for Algebra II

varsity tutors app store varsity tutors android store

Example Questions

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 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 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 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 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

Example Question #42 : Adding And Subtracting Radicals

Subtract the radicals if possible:  \displaystyle \sqrt{40}+\sqrt{8}+\sqrt{50}

Possible Answers:

\displaystyle 2\sqrt{7}+7\sqrt{10}

\displaystyle 5\sqrt{2}+3\sqrt{10}

\displaystyle 13\sqrt2

\displaystyle 2\sqrt{10}+7\sqrt2

Correct answer:

\displaystyle 2\sqrt{10}+7\sqrt2

Explanation:

Evaluate each term.  Write out the factors for each radical and simplify.

\displaystyle \sqrt{40} =\sqrt{4\times 10} = \sqrt{4}\cdot \sqrt{10} = 2\sqrt{10}

\displaystyle \sqrt8 = \sqrt4 \cdot \sqrt2 = 2\sqrt2

\displaystyle \sqrt{50} = \sqrt{25}\times \sqrt{2} = 5\sqrt{2}

Add all the simplified radicals.  Combine like terms.

\displaystyle 2\sqrt{10}+ 2\sqrt2+ 5\sqrt2 = 2\sqrt{10}+7\sqrt2

The answer is:  \displaystyle 2\sqrt{10}+7\sqrt2

Example Question #1421 : Mathematical Relationships And Basic Graphs

Add the radicals, if possible:  \displaystyle \sqrt{18}+\sqrt{50}+\sqrt{200}

Possible Answers:

\displaystyle 6\sqrt3

\displaystyle 24 \sqrt{2}

\displaystyle 9 \sqrt{3}

\displaystyle 18 \sqrt{2}

Correct answer:

\displaystyle 18 \sqrt{2}

Explanation:

Simplify all the radicals to their simplest forms. Use the perfect squares as the factors.

\displaystyle \sqrt{18} =\sqrt{9\times 2}= \sqrt{9}\cdot \sqrt{2} = 3\sqrt{2}

\displaystyle \sqrt{50}= \sqrt{25}\cdot \sqrt{2} = 5 \sqrt{2}

\displaystyle \sqrt{200} = \sqrt{100}\cdot \sqrt{2} = 10\sqrt2

Add the like terms together.

\displaystyle 3 \sqrt{2}+5 \sqrt{2}+10 \sqrt{2} = 18 \sqrt{2}

The answer is:  \displaystyle 18 \sqrt{2}

Example Question #91 : Simplifying Radicals

Simplify: \displaystyle \sqrt{4x^2}-\sqrt{16y^4}

Possible Answers:

\displaystyle 12x-8y^2

\displaystyle 2x-4y^2

\displaystyle 2x-8y

\displaystyle 2x^2-8y^2

\displaystyle 2x-16y^2

Correct answer:

\displaystyle 2x-4y^2

Explanation:

Simplify each radical first.

\displaystyle \sqrt{4x^2}=2x

\displaystyle \sqrt{16y^4}=4y^2

Now, subtract those:

\displaystyle 2x-4y^2

Learning Tools by Varsity Tutors