For which of the following functions is it true that -f(x)=f(-x) for all values of x?

A) f(x)=x+4

B )f(x)=x^2+4

C) f(x)=x^3+4

D) f(x)=x^2+x

E) f(x)=x^3+x

This is a Subject Test question, right?

A useful thing to know is that –*f*(*x*) = *f*(–*x*) will be true only when a function is symmetrical about the origin. That’s only true for choice E.