Her distance from you, d, in feet after t seconds is given by:
d = |100 - 20t|
To find the times when she is 60 ft away from you, we can set d equal to 60 and solve for t:
60 = |100 - 20t|
Now we can solve for t by splitting the equation into two cases:
Case 1: 100 - 20t is positive
60 = 100 - 20t
Subtracting 100 from both sides gives:
-40 = -20t
Dividing by -20 gives:
t = 2
Case 2: 100 - 20t is negative
60 = -(100 - 20t)
Distributing the negative sign gives:
60 = -100 + 20t
Adding 100 to both sides gives:
160 = 20t
Dividing by 20 gives:
t = 8
So she is 60 ft away from you after 2 seconds and 8 seconds.
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 - 20|. At what times is she 60 ft away from you.
She is 60 ft away from you after how many seconds?
1 answer