1.已知函数：y=－1.6x+4,y=0.5x－5,y=4x,y=-3／2x—3,y=5x—7

1.已知函数：y=－1.6x+4,y=0.5x－5,y=4x,y=-3／2x—3,y=5x—7 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 1.已知:x-2y=3,求[(3x+2y)(3x-2y)-(x+2y)(5x-2y)]除4x 的值 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 已知：4x = 5y,求(x+y) ：y 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y 已知4x=5y,那么(3x+y)/(x-2y)= 已知x,y>0 2x+y+3=xy 求5x+4y最小值 （5x+3y)(3y-5x)-(4x-y)(4y+x)=