This question already has an answer here:
I'm reading a book on valuations on a field(Hasse's number theory). He says $(x + y)^s \le x^s + y^s$ for $0 < s \le 1$ and $x, y \ge 0$. I tried to prove it but failed.
Another question: Is $(x + y)^s \ge x^s + y^s$? where, $s \gt 1$ and $x, y \ge 0$.
OK, the first questions is duplicate, but IS THE SECOND QUESTION DUPLICATE, TOO?