Question

11. Solve for x : log(x - 1) + log (x + 1) = log2 1​

Answer 1

log ( x - 1 ) + log ( x + 1 ) = log 21

➡ log ( x - 1 + x + 1 ) = log 21

➡ log 2x = log 21

Therefore, 2x = 21

➡ x = 21 / 2

➡ x = 10.5

_______________________

➡ Log has been taken common in the second step

➡ log 2x = log 21 , here as log is same and there are nothing in the base means 10 , so the bases are also 10 which is equal. As a result 2x = 21