｛X+Y=150 ｛16X：43Y=1：2 ｛X+Y=150｛16X：43Y=1：2

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 ｛X+Y=150 ｛16X：43Y=1：2 ｛X+Y=150｛16X：43Y=1：2 y'/y=1/x 化简 x / y(x+y) - y / x(x+y) = y'-(1/x)y=xe^-x 若x-y=1 化简（x+y)(x^2+y^2)(x^4+y^4)(x^8+y^8)(x^16+y^16) x(x+y)(x-y)-y(y+x)(y-x)=(x-y)( )填空 y(x+y)+(x-y)²-（x+y）（x-y）,其中x=-1/3,y=3 （x-y)(x+y)-(x+y)^2+2y(y-x),其中x=1,y=3. 2y(x+二分之一y)-[(x+y)(x-y)+2y(y+x)],其中|x-1|=2 x>=1,x-y y=x-1(x 已知x+y=a,2x-y=-2a,求[（x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值 x.y都是自然数,且x(x-u)-y(y-x)+12,求x.y得值快1且x(x-y)-y(y-x)=12 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 4x+2y=16 x-y=1, [(y*y*y-y)/(xy+1)*(xy+1)-(x+y)*(x+y)]/[(x+y)*y/(x+1)]其中x=-11,y=1/12,化简再求值. x+x+y+y+y=21 ,x+x+y+y+y+y+y=27 ,x ,y=?