2x-3y=-70 3x+y=90

(x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) (x+y)(2x-3y)=? 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 3x+x+4y+(90+10)x=3y-(2x+y)+510y=34x 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 {(x+2)^2-(y-3)^2=(x+y)(x-y) {x-3y=2 2（x+y)-3(x-y)=3 ,4(x+y)+3(x-y)=15 计算：y(x-y)^2+(y-x)^3=? y'=(2x+y)/(3x-y)微分方程通解 12y(x-y)^2-8(x-y)^3=? x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6