Expand (x+1)(x^2+1)(x-1). What is the sum of the coefficients of the resulting expression?
@ Guest, not exactaly. Maybe you made a mistake in expanding.
We know that (x+1)(x-1) is x^2-1, because of difference of squares. (x^2-1)(x^2+1) is difference of squares, yet again, so this is x^4-1.
I'm not sure if you count constants as expressions or not. If so, then it is 0, if not, then it is 1.