2x-y=6 50%x+12.5%y=3/4
{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
【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=
{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
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于
(x+y)(x+2y)(x+3y)(x+4y)=-40
4x-2y-6y*-y-3x+5y* *=2 就是平方
若5x+3y=3x+4y=x+2y+6,则x+y=___