6x+5y=21 2x-5y=-13 x=1 y=3?

{6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 初二上学期方程题 4x+y=5 5x+4y=63x-2y=1 2x+3y=13x-2y=7 7x+5y=32x+3y=17 2x-y=-4x+5y=6 2x+y=23x-6y=4 3x+2y=52x+y=73x-4y=53x+y=1x-2y=-1x+y=42x+3y=92x-3y=74x+5y=3x+y=20004x+6y=90003x+5y=113x-2y=42x+3y=215x-2y=5x+y=54x+3y=182x+3y=16x+4y=132x+3y=40x 解方程组6(x-y)-7(x+y)=21 2(x-y)-5(x+y)=-1 已知2/y-5/x=16,5/y+6/x=13,求x、y. 6（x-y)-7(xy)=21,2(x-y)-5(x+y)=-1 3x+5y-(x+y)=6 2(x+y)-3x=-7 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 (x+2y)(x-2y)-(2x-y)的平方+(3x-y)(2x-5y)其中x=-1 y=13分之1 X^2-Y^2+6X+10Y-30=0 X^2+Y^2-5X-8Y+21=0 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 (x+y)/6+(x-y)/10=1,(x+y)/6-(x-y)/10=5 （5x-6y)(x+y)=0(x不等于y),则y/x= x*x+2x+y*y-4y+5=0 x= y= 解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7