x+y=20,x-y=10,y=
已知2x-y=10,求[(x²+y²)-(x-y)²+2y(x-y)]/4y
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
) y=cos(x-y)
求y'=y/(y-x)
二元函数f(x,y)=x+y/x-y,求f(y/x,x/y)
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?
[x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013
x+y=5; x^y+y^x=17