6x+y=4x-4y=19找出X和Y

{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 ｛4/(x+y)+6/(x-y)=3 ｛9/(x-y)-1/(x+y)=1 解方程组3(x+y)-4(x-y)=4和(x+y)/2+(x-y)/6=1 常微分y'+4y+y*y=0和dy/dx=x*x*x*y*y*y-x*y的解 已知方程组4X+3Y=6和3X+4Y=15,不解出X,Y,求(X+Y)除以(X-Y)的值. 已知X,Y,满足(X+3Y)(X-3Y)=-10(Y^2-6/5)和2X(Y-1)+4(1/2X-1)=0 已知x.x+y.y-4x+6y+13=0,分别求xy和x.x+y.y的值 找出dy/dx,tan(x y)=x+y 5x=y,5:y=x,3x=4y,3:x=4:y,3;x=y:4,3x+4x=y,3x+4=y y和x成比例吗