Question

A tennis ball is pitched from a machine into the air; the trajectory of the ball can be expressed by the equation y=−0.05x2+45x+3
, taking into consideration that the ball is ejected from the machine 3 feet above the ground. Suppose you were to graph the parabola; at what point would the vertex be located?(1 point)

(8,6.2)


(0,3)


(12,8.4)


(19,0)

Answer 1

Compute the vertex x-coordinate: x = −b/(2a) = −45/(2·(−0.05)) = −45/(−0.1) = 450.
Then y = −0.05(450)^2 + 45(450) + 3 = −10125 + 20250 + 3 = 10128.

So the vertex is at (450, 10128). None of the four provided choices is correct.