Please include the steps that took you to get your answer. I am very confused on what to do with the 1/2.
First let's review how to expand this!
(ax+b)^2=a^2*x^2+2abx+a^2
In this case
(2x^2+1/2)^2=2^2*x^2+2*1/2*2x+(1/2)^2
=4x^2+2x+1/4
Done!