Question

please can anybody help me with this thanks i suck at this type thanks

starting from 100 ft away. your friend skates toward you and then passes you. she skates at a constant speed of 20ft/s. her distance d from you in feet after t seconds is given by d=/100-20t/. at what times is she 60 ft from you?

Answer 1

60= 100 -20t
-100 -100
-40/-20= -20t/-20
2=t

Answer 2

Plug in d = 60 and solve for t.


d=|100-20t|


60=|100-20t|


|100-20t| = 60


100-20t = 60 or 100-20t = -60


-20t = 60-100 or -20t = -60-100


-20t = -40 or -20t = -160


t = -40/(-20) or t = -160/(-20)


t = 2 or t = 8


So she is 60 ft away from you at 2 seconds and at 8 seconds

Answer 3

Oh, didn't see absolute value ha :P