5x-3y=x+2y咋做?

5x-3y=x+2y咋做? 推倒公式:(x+y)(x*x-3x+y*y)=x*x*x+y*y*y怎么做. (2X+3Y)(-2X-5Y)怎么做 (2x-y)(x+y)-(4x-5y)-6=(2x-y+2)(x+y-3) 为什么这么做,原理是什么? 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) (x+y)(x-y)+3y^2怎么做? 已知x平方+y平方-2x+4y+5=0,则4/(y+x/1)咋做的 x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 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 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5 {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? {2x+3y=4 5x-5y=-3{2x+3y=4 5x-5y=-3怎么做， （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