A model rocket is launched with an initial upward velocity of 175 ft/s. The rocket height (h) in feet and t seconds is given by the following
h=175t-16t^2----(exponent 2)
Fine all values for t in which the rockets height is 85 ft.
Round your answer to the nearest hundred. PLEASE HELP!

Question

A model rocket is launched with an initial upward velocity of 175 ft/s. The rocket height (h) in feet and t seconds is given by the following
h=175t-16t^2----(exponent 2)
Fine all values for t in which the rockets height is 85 ft.  
Round your answer to the nearest hundred. PLEASE HELP!<3

anonymous · Answer

Plug in 85 for h and solve for t.

anonymous · Answer

You will be using the quadratic equation

anonymous · Answer

Thanks for trying to help me. That still makes no sense lol

anonymous · Answer

i tried plugging it in but i dont know how to set up the equation right

anonymous · Answer

Im sorry had to step out for a bit. So what you end up getting is 85= 175t-16t^2. And we know that quadratic equation formula works for functions of the form $$ax^2+bx+c=0$$

anonymous · Answer

So you turn your function into that for and you get $$-16t^2+175t-85=0$$(we subtracted 85 from both sides).

anonymous · Answer

and we plug it into the quadratic formula which is $$x= \frac{ -b \pm \sqrt{b^2-4ac} }{ 2a}$$

anonymous · Answer

where a=-16 b=175 and c=-85

anonymous · Answer

Which should leave you with t=0.509s and t=10.43s

anonymous · Answer

There are 2 t's because on is for when the rocket goes up and the other is for when it is on its way down