Can anyone help me with this math?

Question

A ball is thrown from a height of 64 meters with an initial downward velocity of 3 m/s . The ball's height h (in meters) after t seconds is given by the following. h=64-3t-5t^2 How long after the ball is thrown does it hit the ground? Round your answer(s) to the nearest hundredth. (If there is more than one answer, use the "or" button.)

Answer 1

First of all, just so that you are aware, USUALLY the coefficient of the t² term is 4.9 (in the metric system), but we won't quibble here!

In order to find the time of impact, set h(t)=0 and solve the quadratic equation for t.

In the quadratic formula remember that the sign of the squared term is presumed to be positive.

I think yur answer should be between 3 and 4 seconds.