## anonymous 4 years ago Can someone tell me why the answer to this is 4?

1. anonymous

If h(t) represents the height of an object above ground level at time t and h(t) is given by: h(t)=-16t^2+14t+1 find the height of the object when at the time when the speed is zero. h(t)=

2. anonymous

I posted this question before but never got a clear explanation

3. anonymous

speed is zero when it has gone up as far as it can and starts coming back down. that will be at the vertex of this parabola. find the vertex via $-\frac{b}{2a}$ and that will give you the time. replace t by that number and you will get the max height

4. anonymous

here $a=-16, b = 14,-\frac{b}{2a}=-\frac{14}{2\times -16}=\frac{7}{16}$

5. anonymous

then find $h(\frac{7}{16})$a nd i guess (although i did not do it) you will get 4. if not then the answer is whatever you get

6. anonymous

OK THANKS!!!!!!!

7. anonymous

yw