A car left 3 minutes early than the scheduled
time and in order to reach the destination 126
km away in time, it has to slow its speed by 6
km/h from the usual. What is the usual speed
(in km/h ) of the car?
Answers
Answered by
0
Answer:
Not sure about the answer....
Step-by-step explanation:
Hmmm..
Answered by
0
Answer:
126 km/h
Step-by-step explanation:
Let the usual time is t and usual speed is s
Distance =d
d= s x t = 126
because the car left 3 minutes early than the scheduled time so the time is=(t + 3/60)
and he has to slow its speed by 6 km/h from the usual so the speed =(s- 6)
Now-
=(s- 6)(t + 3/60) = 126
=st - 6t + s/20 - 3/10 = 126
=6.30/t - 6t - 3/10 = 0 (s x t=126) (s x t=126 so s/20=6.30/t)
=63/t - 60t - 3 = 0
=60t² + 3t - 63 = 0
t ={-b± √(b2+4ac)}/2at= {-3 ± √(9 + 15120)}/120
= (-3 ± 123)/120
t = 1 hour.
=Usual speed = 126/1 = 126 km/h
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