How to expand squared brackets?

Take, for example, the bracket (a+5)^2. The longer way to do it would be to write (a+5)^2 as (a+5)(a+5) and multiply out that way. However, there is a shorter way where all you have to do is square the first term, square the last term and multiply their product by 2. Therefore, (a+5)^2= a^2 + 10a + 25