①4(x+y)-5(x-y)=51 5(x+y)-4(y-x)=33 ②2x+4y=2 2x-6y=-2分之1 ③ 6x+4y=14 8x-2y=4

5x-4y(y-x)=? x+y／y=5／4,则x／y=---------------- 已知：4x = 5y,求(x+y) ：y （5x+3y)(3y-5x)-(4x-y)(4y+x)= x*x+2x+y*y-4y+5=0 x= y= 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 y=|-x.x+4x+5| 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? （x+y-5)*（x+y-5)+（x-y+3)=0 x*x-y*y 已知:3x-5y=0,求x/y,x-y/y,x-y/x 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 化简求值：2(x+y)(x-2y)-2x(x+y),其中x、y满足x^2+y^2-2x+4y=-5 x+y=5; x^y+y^x=17 已知5x-4y=0,求x:y和x+y:y的值