Have you tried using the website slader? It has answers for all your questions just search up slader on google then search your book on the website.
Notice that both A and B are multiplied by (1/2).
Thus, the given expression can be re-written as [(1/2)(A+B)]^2.
Square the (1/2) and the (A+B) separately, and then multiply together the resulting squares:
(1/4)(A^2 + 2AB + B^2)
If this is correct the answer would be
y^2 + 0.1y + 0.0025