Factorize each of the following expression:

$\frac{1}{16} x^{2} y^{2}-\frac{4}{49} y^{2} z^{2}$

$=y^{2}\left(\frac{1}{16} x^{2}-\frac{4}{49} z^{2}\right)$

$=y^{2}\left[\left(\frac{1}{4} x\right)^{2}-\left(\frac{2}{7} z\right)^{2}\right]$

$=y^{2}\left(\frac{1}{4} x-\frac{2}{7} z\right)\left(\frac{1}{4} x+\frac{2}{7} z\right)$

$=y^{2}\left(\frac{x}{4}-\frac{2}{7} z\right)\left(\frac{x}{4}+\frac{2}{7} z\right)$