Question

explain how to completely factor 2x2 − 8x − 42.

Answer 1

first divide out a 2
-> 2(x^2 -4x -21)
then look for factors of -21 that add up to -4
how about -7 and 3
-7*3 = -21
-7 +3 = -4

->2(x-7)(x+3)