Answer
$(k+4)^{2}=k^{2}+2(k)(4)+4^{2}$
The error in finding the product was missing the term $2(k)(4)$.
Correctly, we have
$(k+4)^{2}=k^{2}+8k+16$.
Work Step by Step
Using square of a binomial pattern $(a+b)^{2}=a^{2}+2ab+b^{2}$ where $a=k$ and $b=4$, we get
$(k+4)^{2}=k^{2}+2(k)(4)+4^{2}$
The error in finding the product was missing the term $2(k)(4)$.
Correctly, we have
$(k+4)^{2}=k^{2}+8k+16$
