My daughter has a problem that I cannot figure out how the teacher's book came up with the answer. They did not provide the intermediate step and there are several like this. If I can see how one is worked, I can figure out the other ones.. Here is the problem....Directions: Factor each polynomial completely.

49x^2 + 28square root of 3 + 12

The answer given is (7x + 2square root of 3)^2

I can get from the answer to the problem but what comes in between!!

Thanks for your help!

Kathy