We are given a polynomial representing the area of a barnyard that is 4x2 + 8x - 21. A rectangle's area is equal to length multiplied by the width which means we can use factoring.
4x2 + 8x - 21
(2x - 3 ) (2x + 7)
we can countercheck this to verify the polynomial.
In this case, the dimensions are 2x - 3 and 2x + 7.