Question

If f(x) = x^3-2x^2 which expression is equivalent to f(i)

Answer 1

remember that
i^2=-1 so

f(i)=i^3-2i^2
i^3=i^2 times i=-1 times i=-i

2i^2=2(i^2)=2(-1)=-2


f(i)=-i-(-2)
f(i)=-i+2

answer is -i+2 or 2-i