若(|x+1|+|x-2|)(|y+1|+|y-3|)接上（|z+1|+|z-4|）=60,求x+2y+3z的最小值和最大值,尽量快.

若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 若x*x+y*y=x+y-1/2,求x,y的值如题 若变量x,y满足约束条件{x>=-1;y>=x;3x+2y 若x+y=1,x不等于0则x+(2xy+y^2)/x/(x+y)/x= [(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y 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] (x/x+y-x/y-x-2xy/x.x-y.y)/(1/x-1/y) 分式化简 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=-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 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（） 1、y-x/x²-y²2、(x-y)(y-z)(z-x)/(z-y)(y-x)(x-z) x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 化简 3x(x^2-x-1)-(x+1)(3x^-x) X^3(x-y)+x(y-x) (x-y)(2x-y-1) 若x.y满足x+=4和x-y=2,求xy分之2x-y+1除以-x分之y+y分之x的值 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