Question

como resolve? log x + log (x - 5) = log 36

Answer 1

$log\ x+log\ (x-5)=log\ 36\\\\ log\ x(x-5)=log\ 36\\\\ x(x-5)=36\\\\ x^2-5x-36=0\\\\ \Delta=25+144\\\\ \Delta=169\\\\ x'=9\\ x''=-4$

Condição de existência

$x-5>0\\\\ x>5\\\\ 9>5\\\\\ x-5>0\\\\ x>5\\\\ -4>5\ nao\ entra$

Solução: S{9}