x+y=200 100x:200y=3:4
{3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-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
(5x+3y)(3y-5x)-(4x-y)(4y+x)=
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
{4/(x+y)+6/(x-y)=3 {9/(x-y)-1/(x+y)=1
(x+y)(x+2y)(x+3y)(x+4y)=-40
3x+4y=100 x+y=33 x+Y=33 求x和y的值,
化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1
X+Y+Z=200,1/3X+4Y+5Z=200,求X,Y,Z等于多少?