If a football player passes a football from 4 feet off the ground with an initial velocity of 36 feet per second, how long will it take the football to hit the ground? use the equation h = −16t2 + 6t + 4. round your answer to the nearest hundredth.
choose one:
a. 0.72
b. 0.65
c. 0.35
d. 0.27

A. 0.72

Step-by-step explanation:

When the ball hits the ground, h = 0.

0 = -16t² + 6t + 4

0 = 8t² − 3t − 2

Solve with quadratic formula:

t = [ 3 ± √(9 − 4(8)(-2)) ] / 16

t = (3 ± √73) / 16

t = 0.72

A. 0.72

Step-by-step explanation:

The football is going to hit the ground when .

So we have to solve the following second order polynomial.

We do this by the bhaskara formula.

Explanation of the bhaskara formula:

Given a second order polynomial expressed by the following equation:

.

This polynomial has roots such that , given by the following formulas:

For the polynomial , we have that:

.

So

The solution is the positive root(there is no negative time).

The correct answer is:

A. 0.72

-2

7 - 9 = -2

reversed:

-2 + 9 = 7