Add.
(7 +2m) + (6 + 4a)
(7 +2m) + (6 + 4a) = (Simplify your answer.)

The function ƒ is defined by ƒ(x) = (x + 3)(x + 1). the graph of ƒ in the xy-plane is a parabola. which interval contains the x-coordinate of the vertex of the graph of ƒ?