90+1.5x=y 100+2x=y y=?

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 90+1.5x=y 100+2x=y y=? y+y'-2y=2x 微分方程y - 2y' + y = x (x-y)(x-2y)+(x-2y)(x-7y),其中X=4,Y=1.5 化简 x / y(x+y) - y / x(x+y) = 填空：x-y/x+y=( )/x^2-y^2 （x-y)2•(y-x)³(x-y)=? [(x-y)²+（x+y）(x-y)]/2xx=3,y=-1.5 (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(x+y)(x-y)-y(y+x)(y-x)=(x-y)( )填空 [3x^2-(x+y)(y-x)][2(-x-y)(y-x)+2x^2+3y^2],其中x=-2分之1,y=1.5 (x-4y)(2x+y)= (x+y)(2x-3y)=? x+y>=2,x-y x+y>=2,x-y