From the first sight, this equation:
$\exp(-2at)=-\exp(-2bt)$
has no solution.
However, Worfram Mathematica clams, it exists. I am wondering, what is the most common to solve it: perhaps, Taylor expansion? Minus in from of the second exponent forbids using the log-mathod. Thank you very much in advance.
Since $\exp$ is a positive function, $-\exp$ will be negative, hence $\exp(\text{whatever}_1)=-\exp (\text{whatever}_2)$ has no real solutions.