`log_5 (x^2 + x) - log_5 (x + 1)` `= 2 ⇒ log_5 ((x^2 + x)/(x + 1))` `= 2` `:.log_5 [ (x (x + 1)/(x + 1)]` `= 2 or log_5 x` `= 2 or x = 5^2` `= 25.`