We are given
[tex]A=24x-x^2[/tex]
where
x is width of rectangle
A is area of rectangle
Since, we have to maximize it
so, we will find it's derivative
and then we can set it to 0
and then we can solve for x
[tex]A'=24\times 1-2x[/tex]
[tex]A'=24-2x[/tex]
now, we can set it to 0
and then we can solve for x
[tex]A'=24-2x=0[/tex]
[tex]x=12[/tex]
So, width is 12 feet
Maximum area:
we can plug x=12
[tex]A=24(12)-(12)^2[/tex]
[tex]A=144ft^2[/tex]
So, the maximum area is
[tex]=144ft^2[/tex]................Answer