to find the factor in ax^2+bx+c form when a>1 multiply a and c together find what 2 numbers add up to b and multiply to ac so
a=3 b=-16 c=-12
ac=3 times -12=-36 factors that add up to -16 2 and -18 is the answer since 2 times -18=-36 and 2-18=-16 so
split the middle number up 3r^2-16r-12=0 3r^2-18r+2r-12=0 group (3r^2-18r)+(2r-12)=0 factor out common factors (3r)(r-6)+(2)(r-6)=0 reverse distribute (ab+ac=a(b+c) so (3r+2)(r-6)=0
