ashish8 wrote:

I was working in this problem

what-is-the-value-of-integer-j-1-j-j-1-2-j-j-81006.html. The answer is D, but I thought B could have two values, 0 and 1.

QUESTION YOU ARE TALKING ABOUT SHOULD READ:

If J\neq{0}, what is the value of J ?(1)

|J| = J^{-1}(2)

J^J = 1 Two reasons why should the stem state that

J\neq{0}:

For statement (1) if

J=0 then we'll have

0^{-1}=\frac{1}{0}=undefined. Remember

you can't raise zero to a negative power.

For statement (2) if

J=0 then we'll have

0^0. 0^0, in some sources equals to 1, some mathematicians say it's undefined. Anyway you won't need this for the GMAT because

the case of 0^0 is not tested on the GMAT. So on the GMAT the possibility of 0^0 is always ruled out.

Also notice that saying in the stem that J is an integer is a redundant.

AS FOR THE SOLUTION:

If J\neq{0}, what is the value of J ?(1)

|J| = J^{-1} -->

|J|*J=1 -->

J=1 (here J can no way be a negative number, since in this case we would have

|J|*J=positive*negative=negative\neq{1}). Sufficient.

(2)

J^J = 1 --> again only one solution:

J=1. Sufficient.

Answer: D.

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