Help me understand this or show me how to use the calculator to get this answer

log4(x-6) + log4(x-3) =1

log4((x-6)(x-3) = 1

log4(x^2-9x+18) = 1  

x^2-9x+18 = 4

x^2-9x+14 = 0

(x-7)(x-2) = 0      x = 7 and 2   but since there are no logs of negatives     x = 7