Answer:
4x^2 + 4xy + y^2
Explanation:
"(2x + y)^2" is an example of "square of a binomial." Among the various algebraic rules there is a formula applying here:
(a + b)^2 = a^2 + 2ab + b^2 (square of a binomial, square of the sum of
two numbers)
It would be worth your while to learn this, as well as
(a - b)^2 = a^2 - 2ab + b^2
Applying the rule (a + b)^2 = a^2 + 2ab + b^2 to (2x + y)^2, we get:
(2x)^2 + 2(2x)(y) + y^2, or, after simplification:
4x^2 + 4xy + y^2