<PRE><B>Question 850419</B>
Area of square = (side)^2


Perimeter of square = 4(side).


The area given is 4z^2-36z+81.


Use A = (side)^2 to find the side. 

sqrt(4z^2-36z+81) = sqrt{(side)^2}


You take it from here. Ok?</PRE>