题目内容：

已知(3x+1)(3x-3)-3x+2)^2=-7,(y+7)(y-7)-y(y-7)=0,求8y^2-5y(-y+3x)+4y(-4y-5/2x)的值

优质解答

(3x+1)(3x-3)-(3x+2)^2=9x^2-6x-3-(9x^2+12x+4)=-18x-7=-7∴ x=0(y+7)(y-7)-y(y-7)=y^2-49-y^2+7y=7y-49=0∴ y=78y^2-5y(-y+3x)+4y(-4y-5/2x)=8y^2+5y^2-15xy-16y^2-10xy=-3y^2-25xy=-3*7*7-0=-147