Question

Factorize:
a² − b² − 4ac + 4c²

Answer 1

$$\begin{gathered} a^2-b^2-4ac+4c^2=\left(a^2-4ac+4c^2\right)-b^2 \\ =a^2-2\times 2a\times c+{\left(2c\right)}^2-b^2 \\ ={\left(a-2c\right)}^2-b^2 \\ =\left(a-2c+b\right)\left(a-2c-b\right) \end{gathered}$$