Question

o valor de x na equação  log (x-8)+ log x =2 log 3 é igual a ;

Answer 1

$log\ (x-8)+log\ x = 2\ log\ 3\\\\ log\ (x-8).x = 2\ log\ 3\\\\\ (x-8).x = 3^2\\\\ x^2-8x = 9\\\\ x^2-8x-9=0\\\\ \Delta = 64+36\\\\ \Delta = 100$

$x^i = 9\\\ x^i^i = -1\\\\\ \boxed{S(-1,9)}$