The absolute value [tex]|a|[/tex] of number [tex]a[/tex] may be thought of as its distance from zero. Definition of absolute value: [tex]\sqrt{a^2}=|a|=\begin{cases} a, \ \ \ \text{jei} \ \ \ a \ge 0 \\ -a, \ \ \ \text{jei} \ \ \ a<0 \end{cases}[/tex]