Respuesta :

factor each
3x^3=3*x*x*x
21x^2=3*7*x*x
36x=2*2*3*3*x

factor out 3x
3x(x^2-7x+12)
what 2 numbers multiply to get 12 and add to get -7?
-3 and -4
3x(x-3)(x-4)
Factor 3x3⁢x out of 3x3−21x2+36x3⁢x3-21x2+36⁢x.
3x(x2−7x+12)3⁢xx2-7⁢x+12Factor.
3x(x−4)(x−3)