Since you need the vertex, and knowing the vertex will tell you the axis of symmetry, it is convenient to put the equation in vertex form.
.. -x^2 -4x +1
.. = -(x^2 +4x) +1
.. = -(x^2 +4x +(4/2)^2) +1 -(-(4/2)^2) . . . . complete the square
.. = -(x +2)^2 +5
The vertex is (-2, 5).
The axis of symmetry is x = -2.
The answer is.... 3.532*10^-4
ANSWER
72 square feet
EXPLANATION
The perimeter of a rectangle is given by:
P= 2l+2w
It was given that, the perimeter of the rectangular mat, is 36 feet.
36= 2l+2w
Divide through by 2.

It was given also that, the length of the mat is twice its width.
This implies that,

Put equation (2) into equation (1) to get,



This means that the length is 12 ft.
The area of the rectangular mat is
