How do you factor # (15x²+22x-5)?

1 Answer
May 4, 2015

In an attempt to find integer based factors:
We are looking for factors of 15 (a×b)
and factors of 5 (c×d)
such that acbd=22

There are only a very few factors available and we should soon come up with (a,b)=(5,3) and (c,d)=(5,1)

Since the final term of the given expression is negative, one of (5,1) needs to be negative;
furthermore, since the coefficient of the middle term is positive
5 must be the positive value and 1 the negative.

Factors:
15x2+22x5=(5x1)(3x+5)