Question 997923
The given values make very poor sense.  "Two feet of fencing" to make a corral will give as largest area, only {{{1/4}}} square foot of area.  The given region to enclose of 1400 square feet is nonsense.


Simply stated, you were given a bad exercise.


Outside of the inconsistent values you were given in your exercise, a lesson is available for a rectangular perimeter - area relationship.  Study it here:
<a href="http://www.algebra.com/my/FIND-RECTANGLE-DIMENSIONS-USING-GIVEN-PERIMETER-AND-AREA.lesson?content_action=show_dev">FIND RECTANGLE DIMENSIONS USING GIVEN PERIMETER AND AREA</a>