x-y+5y-4y

x-y+5y-4y 4x+2y-5x-y 5x-4y(y-x)=? x-y+5x-4y 因式分解(x-2y)(x-3y)+(x-4y)(x-5y)+（x-3y)(x-5y)+(x-2y)(x-4y) 已知：4x = 5y,求(x+y) ：y x+y／y=5／4,则x／y=---------------- (x+y)(x-y)+4(y-1) 4x=5y (y不等于0).则有.y.y/x.x-y.y=? （5x-3y)(3y+5x)-(4y-3x)(3x-4y) (3x-4y)(5x-4y)-(7x-8y)(6y-5x) （5x+3y)(3y-5x)-(4x-y)(4y+x)= 5/4(x+y)(-x-y)^3*[-4/3(x-y)]*[-3/5(y-x)^2] 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 x*x+2x+y*y-4y+5=0 x= y= （x+y）^6/(x+y)^4-(x-y)^5/(x-y)^3 化简 .. (2x-y)(3x-4y)-2(x-y)(2x-5y)简便运算