# How do you factor the expression 16x^4 - 25y^2?

$\textcolor{b l u e}{{a}^{2} - {b}^{2} = \left(a + b\right) \left(a - b\right)}$
So, $16 {x}^{4} - 25 {y}^{2} = \left(4 {x}^{2} - 5 y\right) \left(4 {x}^{2} + 5 y\right)$