#### Built-in functions

Any programming language includes many built-in functions that can be used in arithmetic expressions. To use additional functions, you often have to include maths library:

`#include<cmath> `

For example, the most commonly used standard mathematical functions and their writing in C and C ++

` abs(i) - |i| `

- absolute value of an integer i

` fabs(x) - |x| `

- absolute value of a real числа x

` sqrt(x) -`

\(\sqrt x\)

` pow(x,y) -`

x^{y}

##### Remember!

The function argument is always written in brackets.

For these functions to work, you need to include maths library: `#include<cmath> `