math Q. polynomial func.?

Question

write a polynomial function that has x-intercepts of -1, 1 and 2. write in f(x)=ax^3+bx^2+cx+d form

Answer 1

x-intercepts create factors
x= -1 ==>(x+1)
x =1 ===> (x-1)
x = 2 ===> (x-2)

f(x) = (x+1)(x-1)(x-2) ===> difference of perfect squares
= (x^2 - 1) (x - 2) ===> FOIL
= x^3 - 2 x^2 - x + 2

f(x) = x^3 - 2 x^2 - x + 2

Answer 2

I'm lazy. Just multiply (x-1)(x+1)(x-2) together.