Question

A bicyclist is riding at a speed of 18 mi/h when she starts down a long hill. The distance d she travels in feet can be modeled by d(t) = 41^2 + 18t, where t is the time

in seconds. How long will it take her to reach the bottom of a 400-foot-long hill?

Answer 1

8 seconds

Explanation:

d(t)=400

4t^2+18t=400

4t^2+18t-400=0 subtract 400 from both sides

2t^2+9t-200=0 divide by 2 on both sides

x=8; -25/2 solve using quadratic formula