Question

Log(x)+Log(x-5)=Log(36)

Answer 1

Log(x² -5x) = Log(36)

x² -5x -36 = 0

Δ = (-5)² -4 . 1 .(-36)
Δ = 25 + 144
√Δ = √169     → 13

x = 5 ± 13/2

x' = 9

Log(9) +Log(9-5) = Log(36)
Log(4 . 9) = Log(36)
Log(36) = Log(36)

x'' = -4

Log(-4)+Log(-4-5)=Log(36)
Log(-4 . -9) = Log(36)
Log(36) = Log(36)

S = { 9 , -4}