A train takes 2 hours less for a journey of 300km if its speed is increased by 5 km/h from its usual speed. Find the usual speed of the train.
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✔️For journey of 300km the time usual speed=300/u hr
✔️In increase of 5kmph extra will bring the new time as 300/(u+5) hr
less time
=300/u-300/(u+5)
=300×5/{u×(u+5)}
=1500/{u(u+5)} hr
✔️Accordung to the question it is 2 hr.
So....
1500/u(u+5)=2
=>u²+5u=750
=>u²+5u-750=0
=>(u-25)(u+30)=0
therefore....
u=25 &-30. since the speed can't be negative so the answer is 25 Kmph....
➖➖➖ or ➖➖
For better understanding...
✔️Let n be the usual speed..
✔️n+5 be the faster speed.....
300/n=300/n+5 +2
300(n+5)=300n+2n²+10n
2n²+10n-1500=0
n²+5n-750=0
(n+30)(n-25)=0
n=25 km/h
✔️In increase of 5kmph extra will bring the new time as 300/(u+5) hr
less time
=300/u-300/(u+5)
=300×5/{u×(u+5)}
=1500/{u(u+5)} hr
✔️Accordung to the question it is 2 hr.
So....
1500/u(u+5)=2
=>u²+5u=750
=>u²+5u-750=0
=>(u-25)(u+30)=0
therefore....
u=25 &-30. since the speed can't be negative so the answer is 25 Kmph....
➖➖➖ or ➖➖
For better understanding...
✔️Let n be the usual speed..
✔️n+5 be the faster speed.....
300/n=300/n+5 +2
300(n+5)=300n+2n²+10n
2n²+10n-1500=0
n²+5n-750=0
(n+30)(n-25)=0
n=25 km/h
Shumailahsan:
thnx
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