The exclusion method mentioned on the first floor is actually the best way. . Of course, you can also look at my method;

After observing the inequality, it is found that there is 2 x-5 (-x)

You can get the same form 2 a-5 (-a), so the constructor

F(x) = 2 x-5 (-x), so it is easy to judge that F(x) is the increasing function in R.

f(x)=2^x-5^(-x),f(-y)=2^(-y)-5^(y)，

According to the condition f (x) < = f(-y), so x

x+y & lt； =0. choose B.