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

Answer:

$t \approx 4.501\,s$

Step-by-step 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.

$t \approx 4.501\,s$