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Hi,

This is probably a very common question, but I just dont get it.

It is from the GMAT Prep Test.

If z^n = 1, what is the value of z?

1) n is a non-zero integer
2) z > 0

a) 1 alone is sufficient
b) 2 alone is sufficient
c) both together are sufficient
d) each is individually sufficient
e) they're not sufficient even together

The GMAT Test Prep says the answer is c). I understand that if we take them together we do get an answer, in comparison to taking 2) alone.

However, shouldn't the answer be a) ?

Solution -

If n is non-zero, the way 1 can be the answer is if z = 1. Thus, we got our answer, z = 1.

What's wrong with this?

Thanks

A) is not sufficient.
with A, z=-1 is also possible: (-1)^2 = 1.

Oh! Silly me. Thanks:)