How do you factor #y=x^2 + 3x -18 #?

1 Answer
Dec 15, 2015

Answer:

Factor #y = x^2 + 3x - 18#

Ans: (x - 3)(x + 8)

Explanation:

Find 2 numbers knowing sum (+3 = b) and product (-18 = c). The 2 numbers have opposite signs.
Factor pairs of (-18)--> (-2, 9), (-3, 6). This sum is 3 = b. The 2 numbers are -3 and 6.
Factored form y = ( x - 3)( x + 6)