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Is A^B positive? (1) B^A is positive (2) B is negative [#permalink]
26 Feb 2012, 02:07

1

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

(N/A)

Question Stats:

80% (01:31) correct
20% (00:23) wrong based on 5 sessions

Is A^B positive?

(1) B^A is positive (2) B is negative

Hi, i could not find this question with the search function:

(1) B = negative, then A even and positive B = positive, then A even or odd and positive or negative -->not sufficient

(2) B = negative and if A positive, then A^B positive. But if A negative, then A^B negative --> not sufficient

(1)+(2) B = negative A = must be even and positive --> If A positive, then A^B is positive

Do i think wrong here? Cause the explanation states: Statements (1) and (2) combined are insufficient. Consider B = -2 , A = 2 (the answer is "yes") and B = -1 , A = -2 (the answer is "no").

(1) B = negative, then A even and positive B = positive, then A even or odd and positive or negative -->not sufficient

(1) B^A is positive so when B = negative, then A could be even and positive or even and negative what follows after or is that u have missed consider an example B = -1 , A = 2 or -2, so when A= 2 then B^A = 1 ( positive) and when A = -2, B^A = 1( positive) B=positive...u have done it correctly

(2) B is negative when 1 and 2 combined A^B is positive when A = 2 and B = -1 however A^B is negative when A = -2 and B = -1 hope this expl helps.

_________________

Fire the final bullet only when you are constantly hitting the Bull's eye, till then KEEP PRACTICING.

Re: Is A^B positive? (1) B^A is positive (2) B is negative [#permalink]
26 Feb 2012, 04:34

Expert's post

MSoS wrote:

Is A^B positive?

(1) B^A is positive (2) B is negative

Hi, i could not find this question with the search function:

(1) B = negative, then A even and positive B = positive, then A even or odd and positive or negative -->not sufficient

(2) B = negative and if A positive, then A^B positive. But if A negative, then A^B negative --> not sufficient

(1)+(2) B = negative A = must be even and positive --> If A positive, then A^B is positive

Do i think wrong here? Cause the explanation states: Statements (1) and (2) combined are insufficient. Consider B = -2 , A = 2 (the answer is "yes") and B = -1 , A = -2 (the answer is "no").

Not a good question. First of all on the GMAT possibility of 0^0 wold be ruled out (for example by saying that AB doesn't equal to zero), also most likely A and B would be limited to integers only.

Anyway, the answer is E only: in you post there is perfectly OK example, which satisfies both statements and gives both an YES and NO answer to the question.

Re: Is A^B positive? (1) B^A is positive (2) B is negative [#permalink]
26 Feb 2012, 06:07

Thanks, helped a lot. If the question is not a good one, you might consider to change the wording (or given information) in the gmatclub test (Hardest question, powers, question 10).

Anyway, thanks for the given information...

gmatclubot

Re: Is A^B positive? (1) B^A is positive (2) B is negative
[#permalink]
26 Feb 2012, 06:07