解方程组x+y=6 2x+y=9,

若方程组x+2y=6,2x+y=9 那么x+y=? 解方程组,x+y/2=3x-2y=10+6x+y/4, x+y+xy=5 (x^2)y+x(y^2)=6 解方程组 解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7 解方程组 y=2x x+y=3 解方程组：{x(x+y+z)=6 {y(x+y+z)=9 {z(x+y+z)=10 解方程组：{4/x+y+6/x-y=3 9/x-y-1/x+y=1} 解方程组{4/x+y+6/x-y=3, 9/x-y-1/x+y=1 解方程组 2x+y(y-2x)=9 (x+y)(x+y-3)=10十万火急!求解! 解方程组 3(x+y)-2(x-y)=9,5(x+y)+2(x-y)=-1 解方程组:{3(x+y)-2(x-y)=9,5(x+y)+2(x-y)=-1} 解方程组;x+y/2=x-y/3=6 4(x+y)-3(x-y)=-20 解方程组：2/(x+y)+5/(x-y)=18 9/(x+y)-10/(y-x)=66 解方程组:2/(x+y)+5/(x-y)=18 9/(x+y)-10/(y-x)=66 解方程组 X+Y/2+X-Y/3=6 4[X+Y]-5[X-Y]=2 解方程组2(x-y)/3-x+y/4=-1 6(x-y)-4(2x-y)=16 解二元一次方程组{x+y/2+x-y/3=6,4(x+y)-2=5(x-y) 解方程组2分之x+y+3分之x-y=6 4(x+y)-5(x-y)=2