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# GRE prep Club test question

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GRE prep Club test question [#permalink]  28 Jul 2017, 09:33
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If $$x=5\sqrt{-37}$$ then which of the following must be true?

A. $$\sqrt{(-x)}>2$$

B. $$x >-2$$

C. $$x^2< 4$$

D. $$x^3<-8$$

E. $$x^4>32$$
[Reveal] Spoiler: OA
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Re: GRE prep Club test question [#permalink]  22 Sep 2017, 12:20
saumya17lc wrote:
If x=5√−37
then which of the following must be true?

√−x>2
x>−2
x2<4
x3<−8
x4>32

GREPREP club question- Quant test 6 Question 11 of 20 ID: Q02-99

Just want to add few details in the explanation-

Points to remember- Odd roots have same signs

eg $$3\sqrt{-125}$$ =-5 and $$3\sqrt{125}$$ =5

Now back to question-

we know $$5\sqrt{32}$$=2 so $$5\sqrt{-37}$$≈2.1 ( it should be slightly greater than $$2^5$$)

Now we can check with each option-
only option D fits the sol. because $$(-2.1)^3$$ < -8 so $$x^3$$<−8
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Re: GRE prep Club test question   [#permalink] 22 Sep 2017, 12:20
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