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. (I don't understand these questions at all :/)
9.25 s; 30 ft
4.63 s; 640.5 ft
4.63 s; 1,056.75 ft
4.63 s; 372.25 ft

Question

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.  (I don't understand these questions at all :/)
9.25 s; 30 ft
4.63 s; 640.5 ft
4.63 s; 1,056.75 ft
4.63 s; 372.25 ft

ash2326 · Answer

@ashleyelizabeth Do you know calculus?

anonymous · Answer

no im in algebra one

ash2326 · Answer

Do you know parabolas?

anonymous · Answer

parabola what?

ash2326 · Answer

Parabola like this|dw:1337411285031:dw|

anonymous · Answer

oh! yea

ash2326 · Answer

Ok the function
$$h=-16t^2+48t+30$$
it's a parabola, can you tell me about its concavity ?

ash2326 · Answer

Will it open upwards or downwards?

anonymous · Answer

upwards cause its positive. right?

ash2326 · Answer

$$h=-16t^2+48t+30$$
$$\large -16$$
Think again and tell:)

anonymous · Answer

oops! didnt see that ! downward then

ash2326 · Answer

Ok, Can you find its vertex?|dw:1337411678023:dw|