Setting...
(1)
... You derive immediately that is...
(2)
... so that is...
(3)
Kind regards
The question has a little minor problem: setting...
(1)
... it seems to be that...
a) is ...
b) is increasing with x...
Now is a little difficult to extablish which of the two solutions of the equation...
(2)
... meets both the requirements a) and b), because...
c) vanishes in but is decreasing with x...
d) is increasing with x but is ...
Since it is requested fo find a primitive of (1) and all primitives are defined unless a constant, in my opinion the solution is...
(3)
... even if I'm not 'cent per cent' sure ...