A
akai
![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
Tìm tất cả hàm [tex]f: \mathbb{R}\rightarrow\mathbb{R}[/tex] thỏa mãn 2 điều kiện sau ![Big Grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
[tex]f(x + y)\leq f(x) + f(y)\forall x,y\in\mathbb{R}[/tex]
[tex] \lim_{x\to\infty}\frac {f(x)}{x} = 1[/tex]
[tex]f(x + y)\leq f(x) + f(y)\forall x,y\in\mathbb{R}[/tex]
[tex] \lim_{x\to\infty}\frac {f(x)}{x} = 1[/tex]