solving an equation

Question

The path traveled by a golf ball hit from the ground with a 9-iron can be modeled by the equation y = -0.042x^2 + 5x where x is the distance in yards from the point it was hit and y is the height of the golf ball in feet. When the ball is at its highest point

Answer 1

y = -.042x² + 5x

 

The golfball travels in a parabolic curve.

The highest point will be at the vertex of the parabola.

The vertex is where x=-b/2a, y = f(-b/2a)

V = (-b/2a , f(-b/2a))  ...  a = -.042, b = 5

 

-b/2a = -5/2(-.042) = -5/(-.084) = 59.52381

 

f(-b/2a) = f(59.52381) = -.042(59.52381)² + 5(59.52381) = 148.81 ft

 

The highest altitude reached by the golfball is 148.81 ft

at a distance of 59.52 yds out