Please help me with one Algebra question :)

A ball is thrown into the air with an upward velocity of 28 ft/s. Its height (h) in feet after t seconds is given by the function h = –16t² + 28t + 7. How long does it take the ball to reach its maximum height? What is the ball’s maximum height? Round to the nearest hundredth, if necessary.
1.75 s; 7 ft
0.88 s; 43.75 ft
0.88 s; 17.5 ft
0.88 s; 19.25 ft

Question

Please help me with one Algebra question :)

  A ball is thrown into the air with an upward velocity of 28 ft/s. Its height (h) in feet after t seconds is given by the function h = –16t² + 28t + 7. How long does it take the ball to reach its maximum height? What is the ball’s maximum height? Round to the nearest hundredth, if necessary.
1.75 s; 7 ft
0.88 s; 43.75 ft
0.88 s; 17.5 ft
0.88 s; 19.25 ft

anonymous · Answer

The function is a (negative) quadratic.. Basically, it's an upside down parabola. so, if you can find the vertex, then you have found the maximum height!

anonymous · Answer

Here are 2 ways to find the vertex of a quadratic:
1)  (-b/2a,  f(-b/2a))    Basically, determine what -b/2a is:  in this case, a=-16
b=28 and c=7    so, -b/2a = 7/8  or  .88   Now, plug in  .88 into the equation to determine h..

anonymous · Answer

2) find the axis of symmetry by determining where the x-intercepts are..  then, find the midpoint of those x values...

anonymous · Answer

http://www.mathplane.com/gate_5algebra_ii/quadratics_overview__notes this page contains another example within the notes...