Question

What polynomial has roots of -4, -2, and 5 ?

x3 - x2 - 22x + 40
x3 + x2 - 22x - 40
x3 + 3x2 - 18x - 40
x3 - 3x2 - 18x + 40

Answer 1

Well, one method is to guess and check by plugging in. However! There is an easier way.
A polynomial will have roots when the value of the function is zero.
So (x+4)*(x+2)*(x-5) is definitely one such polynomial.