Questions about the world of GMAT Math from other sources and general math related questions.
gayatri.k
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Number with a sixth root will have an integer square root

by gayatri.k Sat May 09, 2015 7:25 pm

Hello!

Does anyone have a proof / explanation / solution for the following question?

"Any number with an integer sixth root will have an integer square root. Why?"

This question can be found on MGMATs EIVs flash cards, card number 2.

Thank you!

Gayatri
RonPurewal
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Re: Number with a sixth root will have an integer square root

by RonPurewal Wed May 13, 2015 3:39 am

consider what happens when you take the sixth root and cube it.
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Re: Number with a sixth root will have an integer square root

by RonPurewal Wed May 13, 2015 3:42 am

if that hint ^^ is too cryptic, then here are some additional hints:

* if you are "a number with an integer sixth root", then you are 1^6, or 2^6, or 3^6, or, in general, integer^6... and that integer is your sixth root.

* in that case, what is your square root?
it's integer^3.
if you don't see why, just play around with some of the specific numbers listed above. you'll see how it works.

--

most compact explanation possible:
(sixth root of x)^3 = √x
gayatri.k
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Re: Number with a sixth root will have an integer square root

by gayatri.k Fri May 15, 2015 9:21 am

That makes sense! Thank you Ron. :)
RonPurewal
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Re: Number with a sixth root will have an integer square root

by RonPurewal Mon May 18, 2015 5:47 am

you're welcome.
KakakkdeK400
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Re: Number with a sixth root will have an integer square root

by KakakkdeK400 Mon May 25, 2015 10:22 am

Thank you for the informative posts.
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Re: Number with a sixth root will have an integer square root

by RonPurewal Tue May 26, 2015 8:21 am

no problem.