Answer:
f(x) = 3x² - 15x + 12
Step-by-step explanation:
Given f(x) has roots x = a and x = b, then
(x - a) and (x - b) are the factors
f(x) is then the product of the factors
f(x) = a(x - a)(x - b) ← where a is a multiplier
Given roots are x = 4 and x = 1, then
(x - 4) and (x - 1) are the factors
With a = 3, then
f(x) = 3(x - 4)(x - 1) ← expand factors using FOIL
= 3(x² - 5x + 4) ← distribute
= 3x² - 15x + 12
