Question

How do you factor `(x+5)^2 - 81`?

Answer 1

`(x+5)^2-81`
is the same as `(x+5)^2-9^2`

Any expression of the form `a^2-b^2` can be factored as
`a^2-b^2 = (a+b)(a-b)`

For the given example `a=(x+5)` and `b=9`

So
`(x+5)^2 -81 = ((x+5)+9)(x+5-9)`
which simplifies as
`(x+14)(x-4)`