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Mathematics 22 Online
OpenStudy (beccab003):

radical question

OpenStudy (beccab003):

@DanJS

OpenStudy (danjs):

brb 1 min

OpenStudy (beccab003):

\[\sqrt[3]{\frac{ 16 }{ 125 }?}\]

OpenStudy (beccab003):

okay. sorry i didn't know how to get rid of the question mark.

OpenStudy (beccab003):

I'll just start typing through the process. So, with this problem I know that you separate the fraction like this: \[\frac{ \sqrt[3]{16} }{ \sqrt[3]{125} }\] right?

OpenStudy (danjs):

ok, yep you can do that

OpenStudy (danjs):

16 = 2 * 2 * 2 * 2 and 125 = 5 * 5 * 5

OpenStudy (beccab003):

Okay so the top will be \[3\sqrt{2*6}\]

OpenStudy (beccab003):

oh nevermind. that won't work

OpenStudy (beccab003):

\[\sqrt[2]{8*2}\]

OpenStudy (beccab003):

*3

OpenStudy (danjs):

the bottom is easy \[\sqrt[3]{125} = 125^{1/3} = (5*5*5)^{1/3} = [5^3]^{1/3} = 5^{3/3} = 5^{1}=5\]

OpenStudy (danjs):

Recall the nth root of something is the same as that something to the 1/nth power \[\sqrt[n]{x} = x ^{1/n}\]

OpenStudy (beccab003):

yes, i remember.

OpenStudy (danjs):

k, so the cubed root of 125 is 5

OpenStudy (beccab003):

I get that. I was able to input the bottom fraction on my calculator and it came up 5.

OpenStudy (danjs):

right, 125 = 5*5*5 , cubed root of 125 = 5

OpenStudy (danjs):

for the top \[\sqrt[3]{16} = \sqrt[3]{2*2*2*2} = \sqrt[3]{2^3 * 2}\]

OpenStudy (danjs):

overall you get 2 times the cubed root of 2 \[\sqrt[3]{16} = 2*\sqrt[3]{2}\]

OpenStudy (beccab003):

\[\sqrt[2]{2^{3}*2}\] is the same thing as \[\sqrt[3]{8*2}\]

OpenStudy (danjs):

yeah, and 8*2 is 16, the original number

OpenStudy (danjs):

the way i usually try to simplify radicals, is break the number down into its prime factorization first. 16 = 2*2*2*2

OpenStudy (beccab003):

Okay. So final answer: \[\frac{ 2\sqrt[3]{2} }{ 5 }\]

OpenStudy (danjs):

cubed root means you can take out any factor that appears 3 times

OpenStudy (beccab003):

Okay. I will write it out next time so I don't get confused.

OpenStudy (danjs):

16 = 2^3 * 2

OpenStudy (danjs):

yeah that is the final answer

OpenStudy (beccab003):

Thanks! one more? and then I gotta go.

OpenStudy (danjs):

sure

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