(2a-b)(3a+b)+(3d-a)(b+a)=6a2-2ab-3ab-b2+3db+3da-ab+a2= 7a2-6ab+3da+3db-b2
(3x+y)(x-y)-4y(x-y)
3х^2+3ху+ху-у^2-4ху+4у^2
3x^2+3y^2
(2a-b)(3a+b)+(3d-a)(b+a)=6a2-2ab-3ab-b2+3db+3da-ab+a2= 7a2-6ab+3da+3db-b2
(3x+y)(x-y)-4y(x-y)
3х^2+3ху+ху-у^2-4ху+4у^2
3x^2+3y^2