-ln(x - sqrt(x^2 - 1)) = ln(x + sqrt(x^2 - 1))
ln( 1/ (x - sqrt(x^2 - 1)) ) = ln(x + sqrt(x^2 - 1))
1 / (x - sqrt(x^2 - 1)) = x + sqrt(x^2 - 1)
1 = (x + sqrt(x^2 - 1)) * (x - sqrt(x^2 - 1))
Note: (a - b)(a + b) = a^2 - b^2
1 = x^2 - (sqrt(x^2 - 1))^2
1 = x^2 - (x^2 - 1)
1 = x^2 - x^2 + 1
1 = 1
True.