1)f(x)=(x-3)(x+4) = x^2-3x+4x-12 = x^2+x-12
f'(x) = 2x+1 = 0 x = -1/2
2)f(x)=(x+1) = (x^2-4x+4)(x+1) = x^3-4x^2+4x+x^2-4x+4 = x^3-3x^2+4
f'(x) = 3x^2-6x = 0 3x(x-2) = 0 3x = 0 x1 = 0 x-2 = 0 x2 = 2
3)f(x)= = x^2 +2x +1
f'(x) = 2x + 2 = 0 2x = -2 x = -1