A square has an area of x^2+4x+4 square meters. Write an expression that best represents the length of one side of the square.

You have to find the square root of x^2+4x+4, which is:
1) Rewrite x^2+4x+4 as the square of a binomial:
(x+2)^2
2) So now you know that (x+2)(x+2)=x^2+4x+4 (the area)
3) The length is x+2