X+Y=20 X-Y=10

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/+x+y=10,/y/+x-y=12.求x+y的值 已知2x-y=10,求[(x²+y²)-(x-y)²+2y(x-y)]/4y X+Y=7(100X+Y)-(10Y+X)=(10Y+X)-(10X+Y) 已知实数x,y满足|x|+x+y=10、x+|y|-y=12,则x+y的值? 二元函数f(x,y)=x+y/x-y,求f(y/x,x/y) 有这样一道题,计算：（x-y)[(x+y)(x+y)-xy]-(x-y)[(x-y)(x-y)+xy]的值,其中x=20 [x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013 (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai ) y=cos(x-y)