# 13. A catapult launches a boulder with an upward velocity of 148 ft/s. The height of the boulder (h) in feet after t seconds is given by the function h = –16t² + 148t + 30. How long does it take the boulder to reach its maximum height? What is the boulder’s maximum height? Round to the nearest hundredth, if necessary.

A.) 9.25 s; 30 ft

B.) 4.63 s; 640.5 ft

C.) 4.63 s; 1,056.75 ft

*D.) 4.63 s; 372.25 ft

Thank You

1. Well, I am not sure if you are allowed to use physics. that -16 in your equation is negative gravity/2 where g = 32 ft/s^2

If you are allowed to do it that way it is easy
v = 148 - 32 t
at top v = 0
so at top
t = 148/32 = 4.625 seconds to top
then h = -16(4.625)^2 + 148(4.625) + 30
= -342 + 684 + 30
= 372 ft

you could also use calculus on your equation to get t at max h
at top,
dh/dt = 0 = -32 t + 148
leading to the same old t

If you do not know calculus then you must resort to completing the square on that parabola to find the vertex
h = –16t² + 148t + 30

t^2 - 9.25 t - 1.875 = = h/16

t^2 -9.25 t = h/16 + 1.875

t^2 - 9.25 t + 21.4 = h/16 + 23.3
(t - 4.63)^2 = (1/16)( h - 372)
lo and behold, t = 4.63 and h = 372 again

2. thanks Jim!!!!!

If anyone found that confusing what he means to say is that if your in connexus the answer is d.

3. sadly u have to find the answers urself i searched everywhere

4. lmao @boo

5. Thank you Jim do much ;-D

6. Damon literately gives you the answer and Jim has the correct answer. By the way Damon your name is from Vampire Diaries loving it.

7. Thanks both Damon and Jim. Both had correct answer. Both should be appreciated.

8. @Approved I love Damon Salvatore #DelenaAllTheWay

9. we love both JIM and DAMON

10. 41 question exam anyone?

11. 36 for me but its just part 1 and i have 3 parts

12. Thanks 👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍 jim

13. Appreciate it

14. Still D

Reaches a maximum height of 372.25 feet after 4.63 seconds.

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