Question

Factor completely.

4u^2 + 28u + 49

Answer 1

a (2u + 4)^2

b (2u + 7)^2

c (4u – 7)^2

d 2(2u + 7)^2

Answer 2

expand the second one and see what you get

Answer 3

By the equation you can see that the final answer will have only pluses, and you can't factor out a constant right away.. so that eliminates choices c and d.
Deciding between choices a and b should be simple.. look at the last constant and take the square root of it.. what do you get?