Question

A bird flies up and then down again, approximately following the

parabola y = -0.5x^2 + 15x. y measures height in feet.
Approximately what is the highest height that the bird flew to?

Answer 1

Find vertex

x coordinate

• -b/2a
• -15/-1
• 15

Y coordinate (Max height)

• y=-0.5(15)²+15(15)
• y=-0.5(225)+225
• y=112.5ft

Answer 2

• 112.5 ft

Explanation:

The maximum is achieved at vertex of parabola.

The x- coordinate of the vertex is determined by x = - b/(2a).

• x = - 15/(-0.5*2) = 15

The maximum height is the corresponding y- coordinate

• y = - 0.5(15²) + 15(15) = 112.5 ft