Physics, asked by Bellesahrasah8413, 1 year ago

Train takes 3 hours less for a journey 400 km, if its speed is incresed by 6 km/hour form its usual speed

Answers

Answered by amitnrw
1

Distance = 400 km

Let say Usual Speed = S km/Hr

Increased Speed = S+6 km/Hr

Time Taken with Usual Speed = 400/S  Hr

Time Taken with Increased Speed = 400/(S+6) Hr

400/S - 400/(S+6)  = 3


400(S+6) - 400S = 3S(S+6)

400S + 2400 -400S = 3S²+18S

3S²+18S-2400=0

S²+6S-800=0

S²+6S+9-9-800=0

S²+6S+9=809

(S+3)²= 809

S+3 = √809

S = √809 - 3 km/Hr

S = 25.44 km/Hr

Usual speed = 25.44 km/Hr

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