\(a,3x^2-12xy=3x\left(x-4y\right)\)
\(b,x^2+7x-2\left(x+7\right)=x\left(x+7\right)-2\left(x+7\right)=\left(x+7\right)\left(x-2\right)\)
\(c,8x^3-8x^2+2x\\ =2x\left(4x^2-4x+1\right)\\ =2x\left(2x-1\right)^2\)
\(d,x^2-y^2+12y-36\\ =x^2-\left(y^2-12y+36\right)\\ =x^2-\left(y-6\right)^2=\left(x+y-6\right)\left(x-y+6\right)\)