Factorize each of the following quadratic polynomials by using the method of completing the square:

$\mathrm{p}^{2}+6 \mathrm{p}-16$

$=\mathrm{p}^{2}+6 \mathrm{p}+\left(\frac{6}{2}\right)^{2}-\left(\frac{6}{2}\right)^{2}-16 \quad\left[\right.$ Adding and subtracting $\left(\frac{6}{2}\right)^{2}$, that is, $\left.3^{2}\right]$

$=\mathrm{p}^{2}+6 \mathrm{p}+3^{2}-9-16$

$=(\mathrm{p}+3)^{2}-25 \quad[$ Completing the square $]$

$=(\mathrm{p}+3)^{2}-5^{2}$

$=[(\mathrm{p}+3)-5][(\mathrm{p}+3)+5]$

$=(\mathrm{p}+3-5)(\mathrm{p}+3+5)$

$=(\mathrm{p}-2)(\mathrm{p}+8)$