How do you factor completely #15x^2 + 7x - 2#?

1 Answer
Aug 28, 2016

Answer:

#15x^2+7x-2=(5x-1)(3x+2)#

Explanation:

Given:

#15x^2+7x-2#

Use an AC method: Find a pair of factors of #AC=15*2=30# which differ by #B=7#.

The pair #10, 3# works.

Use this pair to split the middle term then factor by grouping as follows:

#15x^2+7x-2#

#=15x^2+10x-3x-2#

#=(15x^2+10x)-(3x+2)#

#=5x(3x+2)-1(3x-2)#

#=(5x-1)(3x+2)#