Question 570796
a rancher has 180 ft of fencing to enclose two adjacent rectangular corrals.
 A river forms one side of the corrals. Suppose the width of each corral is x ft.
Express the total area of the two corrals as a function of x. Find the domain of the function.
:
That would be 3 widths and 1 length, therefore 
L + 3x = 180
L = (180-3x)
:
A = L * X
replace L with (180-3x)
A = x(180-3x)
A = -3x^2 + 180x; total area as a function of x
:
Graph y - -3x^2+180x
{{{ graph( 300, 200, -20, 80, -1000, 3000, -3x^2+180x ) }}}
You can see max area when x=30 ft and domain is 0 to 60