(4x+3y)^2-(2x+3y)(8x-y)-2(6y^2+xy-9)=18
(4x+3y)^2=16x^2+24xy+9y^2
-(2x+3y)(8x-y)=-(16x^2-2xy+24xy-3y^2)=-16x^2-22xy+3y^2
-2(6y^2+xy-9)=-12y^2-2xy+18
16x^2+24xy+9y^2-16x^2-22xy+3y^2-12y^2-2xy+18=16x^2-16x^2+24xy-24xy+ 12y^2-12y^2+18=18
36x^2-12x+1 (3x+1)^3(что надо сделать?)