5x+6y=39 6x -2y=10

6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 已知x,y满足约束条件{2x+5y>=10,2x-3y>=-6,2x+y 3x+2y=6 ,5x+6y=10那么x+y=? 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 已知X,Y,满足(X+3Y)(X-3Y)=-10(Y^2-6/5)和2X(Y-1)+4(1/2X-1)=0 2X+Y+Z=10,X+2Y+Z=-6,X+Y+2Z=8 5X+4Y-3Y=13,2X-3Y+7Z=19,3X-Y=2X 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 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 1.4Y=X 5X+6Y=39