Question

How do you factor `a^2+20a+64`?

Answer 1

In general:
`(a+m)(a+n) = a^2 + (m+n)a + (mxxn)`

Notice that `20 = 16 + 4` and `64 = 16 xx 4`

So `a^2+20a+64 = (a+16)(a+4)`