Answer
$y' = \frac{(1 - y^{2})}{2(xy + 1)}$
Work Step by Step
$xy^{2} + 2y - x = c$
Implicit differentiation: differentiating the equation in terms of $x$
$2xyy' + y^{2} + 2y' - 1 = 0$
Express the formula in terms of $y'$:
$y' = \frac{(1 - y^{2})}{2(xy + 1)}$