Answer:
f(x) = [tex]-3x^{4}[/tex] + 12x³ + 135x²
Step-by-step explanation:
f(x) = -x²(x - 9)3(x + 5) Distribute -x² to (x - 9)
f(x) = -x³ - 9x² 3(x + 5) Distribute 3 to (x + 5)
f(x) = (-x³ - 9x²)(3x + 15) FOIL the two equations
f(x) = [tex]-3x^{4}[/tex] -15x³ + 27x³ + 135x² Combine like terms
f(x) = [tex]-3x^{4}[/tex] + 12x³ + 135x²
