-21x-5y=-104 14x-13y=4二元一次方

-21x-5y=-104 14x-13y=4 -21x-5y=-104 14x-13y=4二元一次方 x+x+y+y+y=21 ,x+x+y+y+y+y+y=27 ,x ,y=? x+x+y+y+y=21 ,x+x+y+y+y+y+y=27 ,x ,y=? {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 （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 x+y=5; x^y+y^x=17 -5y-21x=-7 14x-13y=4 用加减法解 (x+2y)(x-2y)-(2x-y)的平方+(3x-y)(2x-5y)其中x=-1 y=13分之1 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＝ x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 (x-y)^2+5(x-y)-14 (X-Y)(X+Y)=5 能解么 5x-4y(y-x)=? x/2+y/7=13/14,x+y=?