(x-3)2-x(x+5)=2x-6-x^2-5x=x^2-3x-6 (10x+3^2)-4(5x-2)(5x+0,2)=10x+9-4(25x^2+x-10x-0,4)=10x+9-100x^2-4x+40x+1,6=-100x^2+46x+10,6 (2x-y)y^3-2xy^3=2xy^3-y^4-2xy^3=-y^4