Question

A ball is thrown upward with an initial velocity of 48 ft/s from a height 864 ft. h = -16t +48t +864 After how many seconds will the ball reach the ground? (i.e. For what positive value of t is h=0?)

Answer 1

are you sure it is not
h = -16t^2 +48t +864

?

Answer 2

It is! Sorry, bad error!

Answer 3

0 = -16t^2 +48t +864

solve for t

Answer 4

you can divide out by 16

Answer 5

so it'd be -t^2 + 3t + 54 ?

Answer 6

-t^2 + 3t + 54=0
yes

Answer 7

-t^2 + 3t + 54=0

you can even divide by -1 if you want,

t^2-3t-54=0

Answer 8

do you then factor it?

Answer 9

yes

Answer 10

i can't think of any numbers that would work for that particular factoring :/

Answer 11

two number that add up to -3, and multiply into -54?

Answer 12

-9 , 6

-9+6=-3

-9*6=-54

Answer 13

(x-9)(x+6)=0

Answer 14

so the answer would be, the ball will reach the ground in 9 seconds?