Hi

I really need help with these two questions, for the first attachement I have no idea how to do that last part circled in pink

For the second attachement(labeled part e.)), I could not get the answer - I got $\displaystyle \frac{4sqrt{2}}{sqrt{3}}arctan(\frac{sqrt{2}}{sqrt {3}}) + c$ but the answer is $\displaystyle \2\frac{sqrt{2}}{sqrt{3}}arctan(\frac{sqrt{2}}{sqr t{3}}) + c$

Thank you so much in advance!