How do you solve 3x2+5x+2=0 by factoring?

1 Answer
Mar 27, 2015

Assuming 3x2+5x+2 can be factored into
(ax+b)(cx+d) with integer values for a,b,c,d
and noting that all of a,b,c,d will be non-negative (from the form of the original quadratic)
we only have the possibilities
{a,c}={1,3} and
{b,d}={1,2}

There are only 2 combinations to attempt:
(1x+1)(3x+2)
and
(1x+2)(3x+1)

revealing that 3x2+5x+2=0 can be factored as
(x+1)(3x+2)=0

So either
x+1=0 which implies x=1
or
3x+2=0 which implies x=23