linear equation.

Asked by khushal305 | 15th Jul, 2009, 01:26: PM

Expert Answer:

let the speed of the boat in still water be x km/h

 speed of the stream =y km/h

so

speed downstream =x+y

speed upstream =x-y

speed=dist/time

time=dist/speed

so acc to qn

[24/(x-y)]+[28/(x+y)]=6

[30/(x-y)]+[[21/(x+y)]=13/2

putting

1/x-y=a

1/x+y=b

we get

24a+28b=6

i.e.

12a+14b=3...(i)

and

30a+21b=13/2

i.e.

60a+42b=13..(ii)

solving for a , b and then for x , y

 we get

x=10

y=4

 

 

Answered by  | 15th Jul, 2009, 02:09: PM

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