I have been working on Question #4 from the calculus step II module for a while. For part (i) the solutions say that after separating variables and integrating we should arrive at the solution $-\frac{1}{u} = \frac{1}{3} (1+x^2)^{\frac{1}{2}} + c$. I've reworked this problem a few times but I keep ending up at the solution $-\frac{1}{u} = \frac{1}{3} (1+x^2)^{\frac{3}{2}} + c$. Has anyone else had to same problem and can point me in the right direction? Thanks in advance!