5x+y=7.3x-y=1

5x+y=7.3x-y=1 {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 (x+y)/6+(x-y)/10=1,(x+y)/6-(x-y)/10=5 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,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 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 y'/y=1/x 分式的加减:[(x/y-y/x)除以（x+y）+x（1/y-1/x)]除以1+x/y,其中x=5,y=2 x+y=5; x^y+y^x=17 1/x-1/y=x,求5y+xy-5y/y-xy-x=? 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 若(X×X+Y×Y)(X×X+Y×Y-5)=36,则X×X+Y×Y＝ 化简 x / y(x+y) - y / x(x+y) = 5(x-y)³-3（x-y）²+7(x-y)-5(x-y)³+（x-y）²-5（x-y）,其中,x-y=1/3.5(x-y)³-3（x-y）²+7(x-y)-5(x-y)³+（x-y）²-5（x-y）,其中,x-y=1/3先化简,再求值； (X-Y)(X+Y)=5 能解么