To find the time when she is 80 ft away from you, we can set up the equation:
|100 - 20t| = 80
Let's solve for t in this equation.
When 100 - 20t is positive:
100 - 20t = 80
-20t = -20
t = 1
When 100 - 20t is negative:
-(100 - 20t) = 80
-100 + 20t = 80
20t = 180
t = 9
Therefore, she is 80 ft away from you at t = 1 s and t = 9 s.
She is 80 ft away from you at 1 s, 9 s.
Starting from 100 ft away, your friend skates toward you and then passes you. She skates at a constant speed of 20 ft's. Her distance d from you in feet after t seconds is given by d = |100 - 20t| At what times is she 80 from you?
She is 80 ft away from you __ s .
(Use a comma to separate answers as needed.)
1 answer