Answer:
y^2 + 14y +49
Explanation:
A perfect trinomial square is of the form
a^2 +2ab+b^2 = (a+b)^2
or
a^2 -2ab+b^2 = (a-b)^2
In all these a = 1
200 is not a perfect square so it doesnt fit b^2
81 means b=9 2ab = 18 so the second term is out
47 means b = 7 2ab = 14 so this a perfect square trinomial
36 means b = 6 2ab = 12 so the last term is out