#### Answer

$(2r+9)^{2}$

#### Work Step by Step

Given the polynomial
$(2r)^{2}$ + 36r + $(9)^{2}$
We see that the polynomial has the first and last term squared and the middle term is +2 times the first and last term. Thus it follows the rule of
$a^{2}$+2ab+$b^{2}$=$(a+b)^{2}$
In this polynomial a= 2r and b=9
$(2r)^{2}$ + 2(2r)(9) + $(9)^{2}$ = $(2r+9)^{2}$