Find the Length of One of the Longer Sides of the Billboard

Multiple Choice

Find the length of one of the longer sides of the billboard if its area is represented by $x ^ { 3 } - 5 x ^ { 2 } + 3 x + 9$ .

A) $x ^ { 2 } - 6 x - 9$
B) $x ^ { 2 } - 9 x + 6$
C) $x ^ { 2 } + 9 x - 6$
D) $x ^ { 2 } - 6 x + 9$
E) $x ^ { 2 } + 6 x + 9$