there is no exact solution for power-algebric equation
The non-evident root cannot be expressed analyticaly with the combination of a finite number of usual functions.
It can be erxpressed with infinite series (complicated, not useful in practice)
Usally, this kind of equation is solved thanks to numerical computation.
The root can be expressed on a closed form thanks to the Lambert W function :
x = -W(X) where X = -(exp(-1/5)-1)/5