CBSE Class 10 Answered
linear eq.
Asked by | 02 Jul, 2009, 06:23: PM
Expert Answer
let
the speed of the boat in still water be x km/h
and the speed of the stream be y km/h
so speed upstream=(x-y9km/h
speed downstream=(x+y)km/h
speed=dist/time
so
time=dist/speed
so
time taken to cover 100 km downstraem=100/(x+y)
time taken to go 30 km upstream=30/(x-y)
acc to qn,
100/(x+y)+30/(x-y)=6..(i)
simly
7/(x+y)+7/(x-y)=8..(ii)
take x+y=u
and
x-y=v
solve the eqns for u and v
then for x and y.
this is the method
but pl chk the second codition in your question once again.Is it 7 km for sure?
Answered by | 02 Jul, 2009, 10:32: PM
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