Question

What did they do here? see attached.
the original question is integral (x^1/3/(x^1/3-1))dx

Answer 1

\[\int\limits\limits (\frac{ x^{1/3} }{ x^{1/3} - 1 })dx\]

Answer 2

u = x^1/3 - 1
du = 1/3x^-2/3
so then the new integral is
\[3\int\limits\limits (\frac{ u+1 }{ u })du \]
is it not?

my question is,
where does that (u+1)^2 come from?