Question

How do you solve `log_5 (x+10) + log_5 (x-10) = 3`?

Answer 1

`x in {15}`

Explanation:

`log_5 [(x+10)(x-10)] = log_5 125`

`x^2 - 100 = 125`

`x^2 = 225`

`x = ± 15`

But `x + 10 > 0 and x - 10 > 0`