A model jet is fired up in the air from a 18-foot platform with an initial upward velocity of 56 feet per second. The height of the jet above ground after t seconds is given by the equation H = -16t^2 + 56t + 18, where h is the height of the jet in feet and t is the time in seconds since it is launched. What is the maximum height the jet reaches, to the nearest foot?
A. 767 feet C. 30 feet
B. 67 feet D. 18 feet

Question

A model jet is fired up in the air from a 18-foot platform with an initial upward velocity of 56 feet per second. The height of the jet above ground after t seconds is given by the equation H = -16t^2 + 56t + 18, where h is the height of the jet in feet and t is the time in seconds since it is launched. What is the maximum height the jet reaches, to the nearest foot?
A. 767 feet 					C. 30 feet 
B. 67 feet 					D. 18 feet

anonymous · Answer

Please help me!

anonymous · Answer

|dw:1405043330254:dw|  You need to determine the vertex. Do you know how?

anonymous · Answer

Not really.

anonymous · Answer

The vertex represents the highest or lowest point on a parabola like I have drawn. The formula for find in the x value of the vertex in a quadratic equation (ax^2+bx-c) is
-b/2a. So in your equation what will be the x value of the vertex?