The answer should be (x + 2)^2 because when factoring using grouping, you can rid of two x's from the first two terms, and you can factor 4 into 2 * 2. Factoring the first two terms rids of the first and leaves two x's in the second. You can check if i'm right by multiplying (x + 2) (x + 2). This should give x^2 + 2x + 2x + 4. Simplyify this into x^2 + 4x + 4 by combining like terms. Hope this helps.
