Thanks for pointing out that A and C are not complete in my previous posts. I thought correctly but wrote incorrectly. A has typo but C should be revised.

Economist wrote:

Hi GmatTiger,

I could not understand: a) A/B - B/A: If A and B both are -ve, the expression is +ve. out.

if A and B are both -ve, A/B is +ve, and B/A is +ve. Now,

A/B - B/A should be -ve because...magnitude of A is less than B, which means A/B < B/A !!

Similarly,

c) (A^B)-(B^A): If A is -ve integer, and B is +ve integer, the expression is +ve. out.

Here, A^B can be -ve or +ve depending upon B is odd or even,

B^A will be 1/B^A (as A is -ve) , How can u conclude that the expression is +ve ??

bigfernhead wrote:

If |A| < |B| , which of the following numbers is always negative?

a) A/B - B/A

b) A-B/A+B

c) (A^B)-(B^A)

d) A (B/A-B)

e) B-A/B

Is there a fast way of solving these, other than plugging and chugging numbers?

Given that: |A| < |B|

The clue: which of the following is always -ve?

So lets try finding +ve one.

a) A/B - B/A: If

one is +ve and the other is -ve, the expression is +ve. out.

b) (A-B)/(A+B): It is in any case -ve...

c) (A^B)-(B^A): If A is +ve

odd integer, and B is

-ve integer, the expression is +ve. out.

For ex: A = 3 and B = -4:

(A^B)-(B^A) = 3^(-4) - (-4)^3 = 1/81 - (-256) = 256 approx.

d) A (B/(A-B)): If A and B both are -ve, the expression is +ve. out.

e) B - (A/B): If A is -ve (or even +ve) and B is +ve, the expression is +ve. out.

So B.

_________________

Verbal: http://gmatclub.com/forum/new-to-the-verbal-forum-please-read-this-first-77546.html

Math: http://gmatclub.com/forum/new-to-the-math-forum-please-read-this-first-77764.html

Gmat: http://gmatclub.com/forum/everything-you-need-to-prepare-for-the-gmat-revised-77983.html

GT