Question

${log}^{(x + 5)}+{log}^{(x - 4)} = {lg}^{10}$
Por favor me ajudem com esse cálculo!!

Answer 1

Log (x + 5) + Log (x - 4) = Log 10
Log (x + 5)(x - 4) = Log 10
(x + 5)(x - 4) = 10
x² - 4x + 5x - 20 = 10
x² + x - 20 - 10
x² + x - 30

∆ = b² - 4ac
∆ = 1² - 4.1.(-30)
∆ = 1 + 120
∆ = 121

x = -b±√∆/2a

x¹ = 1 + 11/2
x = 12/2
x = 6

x² = 1 - 11/2
x = -10/2
x = -5

S = {-5,6}