Question

A ball is thrown into the air with an upward velocity of 40 ft/s. Its height h in feet after t seconds is given by the function h=-16t^2+40t+6.
A. In how many seconds does the ball reach its maximum height?
B. What's the ball's maximum height?

Answer 1

A) h'(t) = -32t + 40 = 0
-32t = -40
t = 5/4

Answer 2

Test if it's max or min:
h" = -32 < 0 therefore it's max

Answer 3

B) The ball's maximum height therefore occurs at t = 5/4 and the height is:
h(5/4) = -16(5/4)^2 + 40(5/4) +6

Answer 4

wait i dont get what you are doing in the first slide

Answer 5

Taking the derivative of the function.

Answer 6

Did you take calculus?

Answer 7

Yah but you cant square the 32 yet you have to find the t first

Answer 8

no this is Algerbra advance

Answer 9

sorry nanas.. I am doing everything correct, but I don't know how to do this using algebra. Wait actually if u use algebra, just plot the graph.. look at it's highest point, x-value will be the time and y-value will be the height.. This is a parabola pointing down..

Answer 10

I was using calculus and my method works too, but if u don't know it i can just give u answers..

Answer 11

I tried that i guess my brain is to advanced lol
no I dont get how to plo the points but the anwser would be fine

Answer 12

i mean how to plot

Answer 13

just type in the equation and then use trace..
well the answers would be:
A) 5/4
B) -16 * (5/4) ^2 + 40 * (5/4) + 6 <=whatever that equals.. sorry don't feel like doin arithmetic right now.. i actually gotta go to bed lol got a class early 2morro..

Answer 14

t = 10 secs

Answer 15

wow what time is it there

Answer 16

vijay can't be..

Answer 17

10:30 pm

Answer 18

02:30 A.M.

Answer 19

wow its only 7 30 here

Answer 20

vijay t = 10 secs doesn't make sense.. it's t = 5/4

Answer 21

if u use equation v=u+ft

v=0, u=40, f= -10, t= ?

Answer 22

ok What is the lil star thing

Answer 23

he is asking maximum height..

Answer 24

little star is multiplication

Answer 25

time at max height..

Answer 26

1st find the time, then plug the t into the function, u will get height

Answer 27

bahrom is right i remember my online teacher saying this

Answer 28

oh so all i got to do is the multiplication

Answer 29

Okay here's proof:
At t = 10;
h = -16*(10)^2+40*10+6 = -1600 + 400 + 6 is less than 0.. u can't have a negative maximum height.. the ball is still in the air..

Answer 30

yeah just plug in 5/4 for t in the h(t) equation and find the answer..

Answer 31

Please click on become a fan if I helped, I really want to get to the next level!! Thanks =)
I'm off..