Answer:
(1/2)a^n
Explanation:
Let m represent the monomial. The problem statement tells us ...
... m^2 = (1/4)·a^(2n)
Taking the square root, we have ...
... √(m^2) = √((1/4)·a^(2n)) = (√(1/2^2))·√(a^(2n))
... m = (1/2)·a^(2n·(1/2)) = (1/2)·a^n
The monomial is (1/2)a^n.