Let $X$ be a random variable having PDF $f(x) = \frac{1}{\lambda} e^{-\frac{\lambda}{x}} , x > 0 , \lambda > 0$.
And I was trying to find out the $p$th Quantile, for which we have to set $\int_{-\infty}^{x} f(x) dx = p$
so,the $x$ is our $p$th quantile.
$\int_{-\infty}^{x} \frac{1}{\lambda}e^{-\frac{\lambda}{t}}dt = p$
$\int_{-\infty}^{x} e^{-\frac{\lambda}{t}}dt = \int_{0}^{x} e^{-\frac{\lambda}{t}}dt$ as $x > 0$
so,$\int_{0}^{x} e^{-\frac{\lambda}{t}}dt = p\lambda$.
How do I solve this integration next in order to get the value of $x$?