Question

How do you factor `2d^2+4d-126`?

Answer 1

2(d - 7)(d + 9)

Explanation:

`f(d) = 2y = 2(d^2 + 2d - 63)`
To factor y, find 2 numbers, having opposite signs, knowing sum (b = 2) and product (c = -63)
Factor pairs of (-63) --> (-3, 21)(-7, 9). This last sum is 2 = b. There for,
the 2 numbers are -7 and 9.
`f(d) = 2y =2(d - 7)(d + 9)`