#### Answer

$x^{2}+8x+12$

#### Work Step by Step

a.
The length of Kelly's plot is $x+6$ ft.
The width of Kelly's plot is $x+2$ ft.
The area of Kelly's plot is $(x+6)(x+2)$
Table of products$:$
$\left.\begin{array}{rll}
& x & +2\\
\hline x |& x^{2} & 2x\\
+6| & 6x & +12
\end{array}\right.$
$=x^{2}+2x+6x+12$
...gather like terms.
=$x^{2}+8x+12$