Answer
$4x^{2}+36x+81$
Work Step by Step
Step 1: $(2x+9)^{2}=(2x+9)(2x+9)$
Step 2: Using the FOIL method,
$(2x+9)(2x+9)=(2x)(2x)+(2x)(9)+(9)(2x)+(9)^{2}$
Step 3: $(2x)(2x)+(2x)(9)+(9)(2x)+(9)^{2}$=$4x^{2}+18x+18x+81$
Step 4: $4x^{2}+18x+18x+81=4x^{2}+36x+81$
