5X+6Y=139 6x+5y=125求X=?y=?

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知x.x+y.y-6x-8y+25=0,求3x.x+5y的值 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 已知：4x = 5y,求(x+y) ：y x+5y=4 3x-6y=5 求x ,y f(x+y,x-y)=2x②+5xy+2y②+6求f(x,y) 已知3X=4X,5Y=6Z求X+Y：Y+Z |x|=3 |y|=5 |x-y|=|x|+|y| 求 X+Y和 X-Y 等于多少 已知x+y=-5,x*x+y*y=19求xy和（x-y)*(x-y)的值 (1)已知x+y=6,x²-y²=5,求x-y的值（2）若x+y=3,x²+y² √x(√x+2√y)=√y(6√x+5√y,求x-3√xy+2y/x+√xy-6y 已知实数x,y满足根号2x-y的值+5x-6=y-根号y-2x,求x,y的值