[tex]\it Condi\c{\it t}ia\ \ de\ \ existen\c{\it t}\breve a\ \ a\ ecua\c{\it t}iei\ \ este\ \ x>0[/tex]
[tex]\it Not\breve am\ \ lgx=t,\ iar\ \ ecua\c{\it t}ia\ \ devine:\\ \\ t^2-6t+5=0 \Rightarrow\begin{cases}\it t_1=1 \Rightarrow lgx =1 \Rightarrow x_1 =10 >0 \\ \\ \it t_2=5 \Rightarrow lgx=5 \Rightarrow x_2 =10^5 >0 \end{cases}[/tex]
