How do you factor $2d^2 + 7d - 15$ ?

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Answer 1 · 2015-06-04T22:04:36

$2d^2+7d-15 = (d+5)(2d-3)$

I used the quadratic formula to solve this one.

$a=2$ , $b=7$ , $c=-15$

$Delta = b^2-4ac = 49+120 = 169 = 13^2$

So $2d^2+7d-15 = 0$ has roots:

$d = (-b+-sqrt(Delta))/(2a)$

$=(-7+-13)/4$

That is $d = -5$ or $d = 3/2$

Hence factors $(d+5)$ and $(2d-3)$ , respectively.

How do you factor 2d^2 + 7d - 152d^2 + 7d - 15?