Question

At the edge of a cliff, a ball is propelled up into the air, and it comes down over the side of the cliff. The equation h= -4t^2 +45t +312 models approximately the height h feet of the ball after t seconds. How many seconds is the ball in the air before it lands on the ground at the bottom of the cliff?

Answer 1

a)about 5 seconds
b)about 11 seconds
c)about 16 seconds
d) about 45 seconds

Answer 2

it's a quadratic equation of the form
\[at ^{2}+bt+c=0\]
you can find its solution by using this formula:
\[t=\frac{ -b \pm \sqrt{b ^{2}-4ac} }{ 2a }\]

Answer 3

t is 45/8

Answer 4

so the answer would be t~~5.625