# How do you factor 49u^2 - (x-y) ^2?

$49 {u}^{2} - {\left(x - y\right)}^{2} = {\left(7 u\right)}^{2} - {\left(x - y\right)}^{2} = \left[7 u + \left(x - y\right)\right] \cdot \left[7 \cdot u - \left(x - y\right)\right]$
We make use of ${a}^{2} - {b}^{2} = \left(a + b\right) \cdot \left(a - b\right)$