Question

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

Answer 1

$i=\sqrt{-1}\to i^2=-1\\\\f(x)=x^3-2x^2\\\\f(i)=i^3-2(i^2)=i\cdot i^2-2(-1)=i(-1)+2=2-i$