｛x-y=4 ｛5x-y=110 4x-y=－1 9y-x=110

5x-4y(y-x)=? y=|-x.x+4x+5| （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 x+y／y=5／4,则x／y=---------------- 已知：4x = 5y,求(x+y) ：y 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? x-y+5x-4x= ?x-y+5x-4x= ? ｛x-y=4 ｛5x-y=110 4x-y=－1 9y-x=110 x+x+x+y=60 .x-y=4 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 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 7x:4y,x:y=( ):(