(5x^2-7y^2)(7y^2+5x^2)怎么算

解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7 {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 化简:3(x-y)²-7(x-y)+ 2(x-y)²+5(x-y) 计算(x^8-x^7y+x^5y^3-x^4y^4+x^3y^5-x^y^7+y^8)(x^2+xy+y^2) 3x+5y-(x+y)=6 2(x+y)-3x=-7 化简2（2X-7Y)(7Y+2X)+X^2-(-4X+5Y)(-5Y-4X) x+y=1 5x-2y=8 3x-y=7 2x-y=3x表示y和用y表示x 把(x-y)看作一个整体,化解:5(x-y)+2(x-y)-4(x-y)= 3(x-y)把(x-y)看作一个整体,化解:5(x-y)+2(x-y)-4(x-y)=3(x-y)²-4(x-y)+7(x-y)-6(x-y)²= 合并同类项：-3x+2y-5x-7y ｛x+y=7 ｛2x-5y=-21 因式分解：5(x-y)^2+7(x-y)-6 5(2x-7y)-(4x-10y)全过程 5(x-y)^2-7(x-y)-6因式分解 2x-3y+5x+7y合并同类项 x-y/7 - x+y/10 =1/2 2(x-y)-5(x+y)=3修改、、、、（x-y)/7-(x+y)/10=1/2 2(x-y)-5(x+y)=3 化简3(x-y)-7(x--y)+2(y-x) {2x+y/3-2y=0 2(2x+y)-5=7y 5x(x-y)+2y(x-y)