Question

How do you factor `(a^2 + 4)^2 - 25a^2`?

Answer 1

`y = (a^2 + 4 - 5a)(a^2 + 4 + 5a) =`

= `(a^2 - 5a + 4)(a^2 + 5a + 4)`

= [(a - 1)(a - 4)][(a + 1)(a + 4)]