Algebra II : Multiplying and Dividing Radicals

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #41 : Multiplying And Dividing Radicals

\displaystyle \sqrt[3]{4}*\sqrt[3]16{}

Possible Answers:

\displaystyle 2\sqrt[3]{4}

\displaystyle 64

\displaystyle 2\sqrt[3]{16}

\displaystyle 4\sqrt{3}

\displaystyle 4

Correct answer:

\displaystyle 4

Explanation:

When multiplying radicals, we can just multiply the values inside the radicand.

\displaystyle \sqrt[3]{4}*\sqrt[3]{16}=\sqrt[3]{64} This can be simplified to \displaystyle 4 which is the cubic root of the answer.

Example Question #1476 : Mathematical Relationships And Basic Graphs

\displaystyle \frac{10}{\sqrt{50}}

Possible Answers:

\displaystyle 5

\displaystyle \frac{\sqrt{2}}{5}

\displaystyle 2\sqrt{2}

\displaystyle \frac{\sqrt{2}}{2}

\displaystyle \sqrt{2}

Correct answer:

\displaystyle \sqrt{2}

Explanation:

We can simplify \displaystyle \sqrt{50} by finding a perfect square.

\displaystyle \sqrt{50}=\sqrt{25}*\sqrt{2}=5\sqrt{2} Next we can reduce to \displaystyle \frac{2}{\sqrt{2}}.

When dealing with radicals in the denominator, we simplify it by multiplying top and bottom by the radical.

\displaystyle \frac{2}{\sqrt{2}}=\frac{2}{\sqrt{2}}*\frac{\sqrt{2}}{\sqrt{2}}=\frac{2\sqrt{2}}{2}=\sqrt{2}

Example Question #43 : Multiplying And Dividing Radicals

\displaystyle \sqrt{16x}\cdot \sqrt{x^2w^4}

Possible Answers:

\displaystyle 4xw\sqrt{x}

\displaystyle 4w^2\sqrt{x}

\displaystyle 4xw^2\sqrt{x}

\displaystyle 4xw^2

Correct answer:

\displaystyle 4xw^2\sqrt{x}

Explanation:

The first step I'd recommend is to multiply everything and put it all underneath one radical: \displaystyle \sqrt{16x^3w^4}. Then, recall that for every two of the same term, cross them out underneath the radical and put one of them outside. Attack each term separately: \displaystyle \sqrt{16}=4, \displaystyle \sqrt{x^3}=x\sqrt{x}, and \displaystyle \sqrt{w^4}=w^2. Put those all together to get: \displaystyle 4xw^2\sqrt{x}.

Example Question #142 : Simplifying Radicals

\displaystyle 3\sqrt{3}*\sqrt{8}

Possible Answers:

\displaystyle 3\sqrt{24}

\displaystyle 3\sqrt{6}

\displaystyle 6\sqrt{6}

\displaystyle 3\sqrt{24}

\displaystyle 6

Correct answer:

\displaystyle 6\sqrt{6}

Explanation:

\displaystyle 3\sqrt{3}*\sqrt{8}

Combine radicals:

\displaystyle 3\sqrt{24}

Simplify the radical leftover:

\displaystyle 3\sqrt{6*4}

\displaystyle \mathbf{6\sqrt{6}}

Example Question #4141 : Algebra Ii

Divide and simplify:\displaystyle \frac{28\sqrt{24}}{7\sqrt{6}}

Possible Answers:

None of these

\displaystyle 8

\displaystyle 4\sqrt{6}

\displaystyle 16

\displaystyle 6

Correct answer:

\displaystyle 8

Explanation:

\displaystyle \frac{28\sqrt{24}}{7\sqrt{6}}

Divide outside number:

\displaystyle \frac{4\sqrt{24}}{\sqrt{6}}

Divide radicals:

\displaystyle 4\sqrt{4}

Simplify radical:

\displaystyle 4*2=\mathbf{8}

Example Question #42 : Multiplying And Dividing Radicals

Expand, then simplify:  \displaystyle (\sqrt{6}+9)^2

Possible Answers:

\displaystyle 87+18\sqrt{6}

\displaystyle 87+6\sqrt{18}

\displaystyle 87+\sqrt{6}

\displaystyle 87+\sqrt{6}

\displaystyle 87+6\sqrt{18}

\displaystyle 87+18\sqrt{6}

\displaystyle 87+6\sqrt{18}

\displaystyle 87+6\sqrt{18}

\displaystyle 87+18\sqrt{6}

Correct answer:

\displaystyle 87+18\sqrt{6}

Explanation:

\displaystyle (\sqrt{6}+9)^2

\displaystyle (\sqrt{6}+9)^2=(\sqrt{6}+9)(\sqrt{6}+9)

Foil:

\displaystyle 6+9\sqrt{6}+9\sqrt{6}+81

\displaystyle \mathbf{87+18\sqrt{6}}

Example Question #151 : Simplifying Radicals

Simplify:

\displaystyle \sqrt{6}*\sqrt{8}

Possible Answers:

\displaystyle 4\sqrt{3}

\displaystyle 2\sqrt{6}

\displaystyle 4\sqrt{2}

\displaystyle 4\sqrt{6}

\displaystyle 2\sqrt{3}

Correct answer:

\displaystyle 4\sqrt{3}

Explanation:

\displaystyle \sqrt{6}*\sqrt{8} Multiply the numbers inside the radical.

\displaystyle \sqrt{6}*\sqrt{8}=\sqrt{6*8}=\sqrt{48} Factor out a perfect square of \displaystyle 16.

\displaystyle \sqrt{48}=\sqrt{16}*\sqrt{3}=4\sqrt{3}

Example Question #151 : Simplifying Radicals

Simplify:

\displaystyle \sqrt{14}*\sqrt{21}

Possible Answers:

\displaystyle 14\sqrt{2}

\displaystyle 7\sqrt{2}

\displaystyle 21\sqrt{3}

\displaystyle 49\sqrt{3}

\displaystyle 7\sqrt{6}

Correct answer:

\displaystyle 7\sqrt{6}

Explanation:

\displaystyle \sqrt{14}*\sqrt{21} Multiply the numbers inside the radical.

\displaystyle \sqrt{14}*\sqrt{21}=\sqrt{14*21}=\sqrt{294} Factor out a perfect square of \displaystyle 49.

\displaystyle \sqrt{294}=\sqrt{49}*\sqrt{6}=7\sqrt{6}

Example Question #42 : Multiplying And Dividing Radicals

Simplify:

\displaystyle \frac{\sqrt{338}}{\sqrt{169}}

Possible Answers:

\displaystyle 2

\displaystyle \sqrt{2}

\displaystyle 3

\displaystyle \frac{1}{2}

\displaystyle \sqrt{3}

Correct answer:

\displaystyle \sqrt{2}

Explanation:

\displaystyle \frac{\sqrt{338}}{\sqrt{169}} Divide the numbers inside the radicals.

\displaystyle \frac{\sqrt{338}}{\sqrt{169}}=\sqrt{\frac{338}{169}}=\sqrt{2}

Example Question #43 : Multiplying And Dividing Radicals

Simplify: 

\displaystyle \sqrt{7}*\sqrt{5}

Possible Answers:

\displaystyle 7\sqrt{5}

\displaystyle \sqrt{57}

\displaystyle 2\sqrt{3}

\displaystyle \sqrt{35}

\displaystyle 5\sqrt{7}

Correct answer:

\displaystyle \sqrt{35}

Explanation:

When multiplying radicals, simply multiply the numbers inside the radical with each other. Therefore:

\displaystyle \sqrt{7}*\sqrt{5}=\sqrt{35} 

We cannot further simplify because both of the numbers multiplied with each other were prime numbers.

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