## How to create a new file in Linux (CentOS 7)

0 To create a new file in Linux (CentOS 7), type touch filename then press Enter.. filename is the name

## How to change the directory in Linux (CentOS 7)

0 To change the directory in Linux (CentOS 7), type cd target_folder then press Enter.. Target_folder is the name of

## How to clear the screen in Linux (CentOS 7)

0 To clear the screen in Linux (CentOS 7), type clear and press Enter. The clear command will clear whatever

## What is a prime number? (definition and examples)

0 A prime number is a whole number which has exactly two factors: 1 and itself. Examples: 7 is prime,

## Calculate sum of roots x1+x2+x3 (Viete’s relations) – problem with solution

0 This is problem 3 from Learn Math (problems with solutions) [volume 2].   0

## Calculate |3-7i| (module of complex number)

0 This is problem 2 from Learn Math (problems with solutions) [volume 2]. 0

## Prove that x^3 + x + tan x is an odd function

0 This is problem 1 from Learn Math (problems with solutions) [volume 2]. 0

## Calculate cos 2x, where sin x = 1/7 (partial solution)

0 This is problem 2 from Learn Math (problems with solutions) [volume 1]. The free ebook contains the full solution.