after completing a journey of 84km a cyclist noticed that he would take 5 hours less if he could travel at a speed which is 5 km/hr more what was the speed of the cyclist in km/hr...
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Answers
Answer:
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Answer:
Distance = s × t
⇒ 84 = s × t
If speed had been 5 km/hr more, time would have been 5 hrs less.
⇒ New speed = s + 5
⇒ New time = s - 5
(s + 5)(t - 5) = 84
s(t - 5) +5(t - 5) = 84
st - 5s + 5t - 25 = 84
5t - 5s + st = 84 + 25
5t - 5s + st = 109
5(t - s) + 84 = 109
5(t - s) = 109 - 84
5(t - s) = 25
t - s = 5
t = 5 + s
(s + 5)(5 + s - 5) = 84
s(5 + s - 5) +5(5 + s - 5) = 84
5s + s² -5s + 25 + 5s - 25 = 84
s²+ 5s = 84
s² + 5s - 84 = 0
s² + 12s - 7s - 84 = 0
s(s + 12) - 7(s + 12) = 0
(s - 7)(s + 12) = 0
s = 7, -12 km/hr
Since speed can't be negative, s = 7 km/hr.
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