x/y=9/20 x/(y+16)=1/4 x是多少把解题过程一字不漏的写出来

先化简再求值 x(9x-y)-y(y-x)+(x-y)的平方,其中x=-1,y=2 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 y'/y=1/x 化简 x / y(x+y) - y / x(x+y) = {5(x-3y)-6=2x+1 3(x+6y)+4=9y+19 ｛3分之2（x-y）=4分之x+y-1 6）x+y)=4(2x-y)+16 y'-(1/x)y=xe^-x 9y=3x-(x-1),4(x+y)-(2x+4)=8y 已知y/x=9/10则(1-y/x)[x/(y-x)]? x>0 y>0 x+y=1,4/X+9/y最小值x>0 y>0 x+y=1,求4/X+9/y最小值 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+(9-8-y)=10 y+y-(9-8-y)=2 x-y=xx-9.9x xy=11y-1 y=? x=? x+y-xy=?x+(9-8-y)=10y+y-(9-8-y)=2x-y=xx-9.9xxy=11y-1 y=?x=?x+y-xy=? x>=1,x-y y=x-1(x x+y=5① x=3y+2① 9x-5y=1① 3x-2y=11① x-2y=y+1① 2x-y=7② x+3y=8② 6x-7y=2② 2x+3y=16② 2x-3y=10②3x+2y=y+1①2x-3y=10②D