Question

x^2 + ax + b = (x + c) (x + d)

how do you get c and d from a and b?

Answer 1

Why not go the other way?

b = c*d
a = ???

Answer 2

I'm trying to understand factoring and we've been starting fro x^2 + ax + b = 0

Answer 3

Well, it does not hurt to work backwards. Very often, this leads to greater understanding.

(x + c) (x + d) = x^2 + (c+d)x + cd

Thus a = c+d and b = c*d. These are very important relationships.

You must find FACTORS of b that will SUM to a. This is the heart of factoring.

Answer 4

thank you! exactly what I was looking for. that really helps.