Question

A falling object travels a distance given by the formula d= 3t + 3t ^2, where d is measured in feet and t is measured in seconds. How many seconds will it take for the object to travel 50 feet?

Answer 1

3.61 sec

Explanation:

Set the given d= 3t + 3t ^2 equal to 50 and solve for t:

3t^2 + 3t - 50 = 0

This is a quadratic equation with coefficients 3, 3 and -50. The discriminant is b^2 - 4ac, or 3^2 - 4(3)(-50), or 9 + 600 = 609

The roots of this quadratic are therefore:

-(3) ± √609 -3 ± 24.68 21.68

t = -------------------- = ------------------- = ----------- = 3.61 sec

2(3) 6 6