@KarlDeux

It's not exactly 2×ln(abs(x))+C.
It's 2×ln(-x)+C1 for x<0, and 2×ln(x)+C2 for x>0, with C1 and C2 reals but not automatically equal.
Because of the discontinuity in 0, there's a constant for x<0 and another one for x>0.

@OhsohLibre

Any suggestions for any type of media for someone who finished calc 3 years ago and looking to jump back in again for a hobby?