I have these two equations 

[![enter image description here](https://i.stack.imgur.com/ggDBy.png)](https://i.stack.imgur.com/ggDBy.png)
[![enter image description here](https://i.imgur.com/axhkd1x.png)](https://i.imgur.com/axhkd1x.png)

and I need to convert them to C code where you input`k` and `x`. The thing is I don't get that advanced levels of math, neither did I learn C in the past :D

Can anyone show me step by step what built-in functions can be used for this and how exactly should the logic behind the app work?

Cheers!