Select the correct answer.
this table represents a quadratic function.

x y
1 3
3 -3
5 -5
7 -3
9 3

which statement about this function is true?
a. the value of a is positive, so the vertex is a maximum.
b.
the value of a is positive, so the vertex is a minimum.
c.
the value of a is negative, so the vertex is a minimum.
d.
the value of a is negative, so the vertex is a maximum.

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters