请教一道数学题

 x^y≤y^x? 条件一: √x=y；条件二: x=2y

我觉得条件都不充分。。。。。。。。

寻求高见中。。。。。

觉得是C

他们单独都没法判断。

由（1）（2）可得x＝0，y＝0， 或者x＝4，y＝2

把这两组数代进去都是x^y≤y^x。。。

possible solution:
     Obviously, neither of the two conditions is sufficient.

     According to squr(x)=y, x=y^2, x^y = y^2y (x,y>=0)

     for y>1, as long as 2y<=x, x^y<=y^x

     for y=1, x=1, x^y=y^x

     for y<1. as long as 2y>=x, x^y<=y^x

therefore, by holding condition (1)+(2) together, x^y = y^x, which is ok!

合起来的话X=Y，X=2Y矛盾。。。。。