Respuestas

  • Usuario de Brainly
2013-12-08T15:30:31+01:00
2log(x + 5) = log(x + 7)
log(x + 5)² = log(x + 7)
log(x² + 2*5*x + 5²) = log(x + 7)
log(x² + 10x + 25) = log(x + 7)
(x² + 10x + 25) = (x + 7)
x² + 10x - x + 25 - 7 = 0
x² + 9x + 18 = 0

x =  \frac{-9 \frac{+}{} \sqrt{9^2-4*18*1}}{2*1}

x =  \frac{-9 \frac{+}{} \sqrt{81-72}}{2}

x =  \frac{-9 \frac{+}{} \sqrt{9}}{2}

x =  \frac{-9 \frac{+}{} 3}{2}

Solución:
x₁ = -3  Válida
x₂ = -6  Válida