Factor.

49-4u?

What is the final answer?

(7 + 2√u) (7 - 2√u)

Step-by-step explanation:

There are two terms here, 49 and - 4u. These terms have nothing in common, so any factors will not be rational unless u is a positive perfect square.

However, we could rewrite 49 - 4u as 7^2 - [2√u]^2, which is the difference of two squares. This latter result can be factored as

(7 + 2√u) (7 - 2√u)