Chapter 10 - Introduction to Differential Equations - Chapter Review Exercises - Page 526: 8

$$ y=\tan^{-1}(x+1) .$$

By separation of variables, we have $$ \sec^2ydy= dx $$ then by integration, we get $$ \tan y=x+c .$$ Now, since $y(0)=\pi/4$, then $c=1$. So the general solution is given by $$ y=\tan^{-1}(x+1) .$$