Answer
$(m+3n)^{2}$=$m^{2}$+6mn+$9n^{2}$
Work Step by Step
To simplify the product $(m+3n)^{2}$ we'll apply the rule that states that
$(a+b)^{2}$=$a^{2}$+2ab+$b^{2}$ and set a=m and b=3n
Therefore,
$(m+3n)^{2}$ =$m^{2}$+2(m)(3n)+$(3n)^{2}$
=$m^{2}$+6mn+$9n^{2}$
