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