Question

How do you factor `4x^2+17x-15`?

Answer 1

Factor: y = 4x^2 + 17x - 15 (1)

Ans: (4x - 3)(x + 5)

Explanation:

y = 4(x - p)(x - q)
I use the new AC method to factor trinomials.
Converted trinomial: `y' = x^2 + 17x - 60`= (x - p')(x - q')
p' and q' have opposite sign.
Factor pairs of -60 -->( -2, 30)(-3, 20). This sum is 17 = b.
Then p' = -3 and q' = 20
Therefor, `p = (p')/a = -3/4`, and `q' = 20/4 = 5`

`y = 4(x - 3/4)(x + 5) = (4x - 3)(x + 5)`