2x+3y=6和4x+6y=12

解方程组3(x+y)-4(x-y)=4和(x+y)/2+(x-y)/6=1 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 已知X,Y,满足(X+3Y)(X-3Y)=-10(Y^2-6/5)和2X(Y-1)+4(1/2X-1)=0 解方程组：x+y/2+x-y/3=6 4(x+y)-5(x-y)=12 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 若x和y满足x^2+y^2=6x-4y-17,则2x-3y的最大值和最小值的和是多少? ｛4/(x+y)+6/(x-y)=3 ｛9/(x-y)-1/(x+y)=1 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于