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?

3.61 sec

Step-by-step 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