Answer:
f(x) x^3 - 2x^2 + 5x + 12
Explanation:
Next time please share the goal. I'm guessing your intent was to multiply out the given function.
f(x) = (x^2 + x - 3x - 3)(x - 4), or
= (x^2 - 2x - 3)(x - 4)
Now apply the distributive property of multiplication:
f(x) = x^3 - 4x^2 - 2x^2 + 8x - 3x + 12, or
= x^3 - x^2(4 - 2) + x(5) + 12, or
f(x) x^3 - 2x^2 + 5x + 12