[tex]a)~| \frac{x}{-1} |=|-x|=-x~(pentru~ca~x\ \textless \ 0). \\ \\ b)~ | \frac{x}{-1} |=|-x|=x~(pentru~ca~x\ \textgreater \ 0). \\ \\ c)~ | \frac{3}{x}|= -\frac{3}{x}. \\ \\ d)~ | \frac{3}{x} |= \frac{3}{x}. \\ \\ e)~|x-5|=5-x. \\ \\ f)~|-x+1|=-x+1 . \\ \\ g)~ \frac{x}{|x|} = \frac{x}{-x}=-1. \\ \\ h)~- \frac{|x|}{x} =- \frac{x}{x} =-1.[/tex]
[tex]De~retinut: \\ \\ |x|= \left \{ {{x,~daca~x \geq 0} \atop {-x,~daca~x\ \textless \ 0}} \right. .[/tex]