## Calculus (3rd Edition)

$$2xy^2$$
The mistake is to differentiate $y^2$ with respect to $x$ as $2y$. The correct formula is $$\frac{\partial }{\partial x}(x^2y^2)=\frac{\partial x^2}{\partial x}y^2+\frac{\partial y^2}{\partial x}x^2=2xy^2+0=2xy^2.$$