若y=1-x(x

若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 若x-y=1,求代数式x(x-y)+y(y-x)+2013的值 若x*x+y*y=x+y-1/2,求x,y的值如题 若实数x,y满足x-y+1》=0,x+y>=0,x 若变量x,y满足约束条件{x>=-1;y>=x;3x+2y 若实数x,y满足x-y+1>=0,x+y>=0,x 若(-x+6):(x-y):(4x+y)=3:14:1,求x+y 若(-x+6):(x-y):(4x+y)=3:14:1,求x+y 若x+y=1,x不等于0则x+(2xy+y^2)/x/(x+y)/x= 若y=1-x(x 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 若√x-1-√1-x=(x+y)²先化简再求值：（1/2x）-(1/x+y)[x²-y²+(x+y/2x] 若x=-1/4,能否确定代数式(2x-y)(2x+y)+(2x-y)(y-4x)+2y(y-3x)的值? 若|x+y-1|+（x-y-2)²=0,求代数式（x+2y)(x-2y）-（2x-y)(-y-2x)的值. 若x-y=1 化简（x+y)(x^2+y^2)(x^4+y^4)(x^8+y^8)(x^16+y^16) 若x+y=4,则多项式1/2(x+y)+4(x-y)-3（x-y）-3/2(x+y)-x+y值是（） x>=1,x-y y=x-1(x