Smith and Slerry have $24\;m$ of fencing to enclose a rectangular garden at the back of their house express the area of the garden as a function of its width.

Question

$\begin{array}{1 1} (a)\; 24+2x^2 \\ (b)\; 2x^2-24 \\ (c)\; 24-2x^2 \\ (d)\; \text{none of the above} \end{array}$