Question

A ball's height above the ground is modeled by the equation h(t) = -16t^2 + 80t + 40
When does the ball hit the ground?

Answer 1

set h(t)=0
and then solve for t

Answer 2

I tried, but I got 8(-2t^2+10t+5) = 0
what do I now?
@baru

Answer 3

\(-2t^2 + 10t + 5=0\)

this is a quadratic equation. you have to use the quadratic formula

Answer 4

\[t = { -10 \pm \sqrt{140}}\]

Answer 5

yes, simplify that, use a calculator

Answer 6

also, have you done the quadratic formula correctly?
\[\frac{ -b \pm \sqrt{b^2-4ac} }{ 2a }\]

Answer 7

over -4

Answer 8

? i dont get what u mean

Answer 9

oh, ok, yes your answer over -4

Answer 10

I have to go to class sorry. ty though.

Answer 11

sure :)