Answer:
Option 3
Explanation:
log4(x) + log4(x - 3) = log4(-7x + 21)
log4(x² - 3x) = log4(-7x + 21)
x² - 3x = -7x + 21
x² + 4x - 21 = 0
x² + 7x - 3x - 21 = 0
x(x + 7) - 3(x + 7) =0
(x + 7)(x - 3) = 0
x = -7, 3
-7 and 3, both are e extraneous solutions because logs of non-positive numbers don't exist
At x = 3,
-7x + 21 = 0