How do you multiply [(x^2-4x+4) -i^2] × (x+1) together

The answer is -x^3 +3x^2+x+5 but can you show me how my teacher got that?

i is an imaginary number and i=√-1

[(x^2-4x+4)-i^2] times (x+1)
[x^2-4x+4-(√-1)^2](x+1)
[x^2-4x+4-(-1)](x+1)
(x^2-4x+4+1)(x+1)
(x^2-4x+5)(x+1)
x^3+x^2-4x^2-4x+5x+5
x^3-3x^2+x+5

Your teacher made a mistake.