2x^n

Question

-2x^n<0? (n: integer)

1) x<0
2) n: odd



cf) what if the question is (-2x)^n<0?

ccax · Answer

It's C.

If x<0 and n is an odd integer, then x^n is negative and
-2 x^n postive. (1) and (2) alone are not sufficient because
(1) with n even is positive, and (2) with x>0 is positive, too.

If the question was (-2x)^n<0, then the answer would be
A.

If x<0, then -2x > 0 and (-2x)^n > 0 no matter what n would be.

sherinaparvin · Answer

from (1) if n is odd -2x^n >0 , if even then it is <0 Hence not sufficient. From (2) if x <0, then -2x^n >0, if x >0 , -2x^n <0 Hence not sufficient. But together they are sufficient Answer is C

sm176811 · Answer

Agreed its C!

GMAT Trick... should consider 0!

gmatacer · Answer

Answer is C

from option 1 > we can't realy say because n can be odd or even
from option 2 > x can be +ve or -ve

combining both gives us the answer!

2x^n<0? (n: integer) 1) x<0 2) n: odd cf) what if the

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