Question

A golfer hits a ball from a starting elevation of 7 feet with a velocity of 70 feet per second down to a green

with an elevation of -2 feet. The number of seconds t it takes the ball to hit the green can be represented



by the equation - 16t2 + 70t +7=-2. How long does it take the ball to land on the green?



It takes the ball ___



seconds to land on the green.

Answer 1

`t \approx 4.501\,s`

Explanation:

The second-grade equation must be rearragend into its standard form:

`-16\cdot t^(2) + 70\cdot t + 9 = 0`

Roots can be found with the help of the General Equation for Second-Order Polynomial:

`t = \frac{-70\pm \sqrt{70^(2)-4\cdot (-16)\cdot (9)}}{2\cdot (-16)}`

`t = 2.188 \pm 2.313`

`t_(1) \approx 4.501\,s`

`t_(2) \approx -0.125\,s`

Only the first root offers a reasonable solution.

`t \approx 4.501\,s`