$\left(x^2-6x\right)\cdot 2x-2x^2\left(6-x\right)=x\left(x-6\right)\cdot 2x-2x^2\left(6-x\right)=-2x^2\left(6-x\right)-2x^2\left(6-x\right)=\left(-4x^2\right)\left(6-x\right)=4x^2\left(x-6\right)=4x\left(x^2-6x\right)=-4x\left(-x^2+6x\right)$