Respuesta :
Here is your answer
Given area is
z^2 + 18z + 81
= z^2 + 2× z × 9 + 9^2
[using (a+b)^2= a^2 + 2ab + b^2], we get
= (z+9)^2
we know that area of a square is represented by side^2.
So, here
Side of square is
[tex]<b> z+9 </b>[/tex]
HOPE IT IS USEFUL