If x is an integer and x is not equal to zero, which of the following are always positive and which are always negative?

a: -x to the power of 4
b: (-x) power of 4
c: x to the power of 4
d: x
e: -x

Any negative number squared is positive.

(-x)^4 = (-x)^2 * (-x)^2

If a is -(x^4), then it is negative.

The only other negative I see is e.