lg(x la puterea 2 +5)=lg9

Răspuns :

lg(x²+5)=lg9
⇒x²+5=9
⇒x²=4
⇒x ∈{-2,2}
   
[tex]\displaystyle\\ \lg(x^2 +5)=\lg9 \\\\ \Longrightarrow ~~~x^2+5=9\\\\ x^2 = 9-5\\\\ x^2 = 4\\\\ x = \sqrt{4} = \boxed{\bf2} \\\\ \texttt{Nota: Solutia negativa nu este admisa.}[/tex]