algebra
posted by Brynn on .
The height above ground of a rock dropped from a bridge can be found using the formula h(t) = 9.8tsquared + 100, where t represents the number of seconds.
What is the height of the rock after 3 seconds?
How long will it take the rock to hit the bottom?

Your equation should read
h(t) = 9.8t^2 + 100
when t = 3
h(3) = 9.8(9) + 100
= 11.8
it will be 11.8 m above the ground
how long to hit ground ??
when h(t) = 0
0 = 9.8t^2 + 100
9.8t^2 = 100
t^2 = 100/9.8 = 10.204..
t = √10.204.. = appr 3.2 seconds