for
ax²+bx+c
if a≠1 then use the ac method
1. multiply a and c
2. factor the result such that they add to get b
3. split b up into those 2 factors
4. group and undistribute
so
12x²-1x-6
ac=12*-6=-72
what 2 factors add to -1?
-9 and 8
12x²+8x-9x-6
group
(12x²+8x)+(-9x-6)
undistribute
4x(3x+2)+(-3)(3x+2)
undistribute
(4x-3)(3x+2)