Answer:
f(x) = (x + 11) (x + 3) (x − 1) (x − 3)
Step-by-step explanation:
f(x) = x⁴ + 10x³ − 20x² − 90x + 99
f(x) is a fourth order polynomial, so it has 4 roots. Use rational root theorem to find possible rational roots.
±99, ±11, ±9, ±3, ±1
By trial and error, the zeros are -11, -3, 1, and 3.
f(x) = (x + 11) (x + 3) (x − 1) (x − 3)
