Question

If f(x) = x^3 – 2x^2, which expression is equivalent to f(i)?
A.–2 + i
B.–2 – i
C.2 + i
D.2 – i

Answer 1

whats stopping you from plugging in x = i

Answer 2

Remember, \(i^2=-1\).

Answer 3

And also, \(i = \sqrt{-1}\)

Answer 4

\[\large \begin{align}f(\color{red}{x}) &= \color{red}{x}^3-2\color{red}{x}^2\\~\\~\\f(\color{red}{i}) &=?\end{align}\]

Answer 5

\[(i)^3 = i^{2+1}=(i)^2 \cdot i\]

Answer 6

Thanks a lot

Answer 7

Both of you