(x+y)^2-9y^3

3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 81/8*(-x-y)^6*(x-y)^3*4/9(x+y)^4*(y-x)^2 计算(x-y)^7÷(y-x)^6+9-x-y)^3÷(x+y)^2 (x+y)^2-9y^3 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) (x^2y-9y)/(xy+3y) x+3y+9y^2/(x-3y)+6x^2y/(9y^2-x^2) x^3y^2+6x^2y+9x x(x-y)2-(y-x)3 [(3x+y)(x-y)-(2x+3y)(x-y)]*(x-y) 计算：x+2y/x-y+2x/y-x-3y/x-y 化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方 常微分方程的通解dy/dx=(x-y+1)/(x+y-3)y^4=2y^n+y=0y''+6y'+9y=e^(-3x)y''+y'-2y=4e^(2x) 已知2x-y/x+2y=3,求2(2x-y)/x+2y-9(x+2y)/2x-y+3的值. [(1/9(x+y)^3-2(x+y)^2-2/3(x+y)]÷x+y/3x+y/3x+y是整体.. 3x-2y=9 x-3y=2 x+y=5 x+2y=3 y=x 2x+y=8 3y=2x y/3=x/2 12/x=9/y y/x=?y/x=?x/y=?