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supernova1203
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Homework Statement
A jet flew from Tokyo to Bangkok, a distance of 4800 km. On the return trip, the speed was decreased by 200km/h. If the difference in the times of the flights was 2 hours, what was the jet's speed from Bangkok to Tokyo?
Homework Equations
Distance=(speed)(time)
Time=Distance/Speed
Speed=Distance/Time
The Attempt at a Solution
On sample questions they showed us how to solve a problem like this, i attempted to solve it in a similar manner however as you will see i was unable to
Let x represent speed
D=4800 Speed=? Time =?
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Distance Speed Time
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A to B 4800 x 4800/x (since time = d/s)
Tokyo
to Bangkok
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B to A 4800 (x-200) 4800/(x-200)
Bangkok Since on return
to Tokyo trip speed was
reduced by 200
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Time -2
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4800/x +4800/(x-200)=-2
Lowest common denominator = x(x-200)
Here we multiply everything by x(x-200)
4800/x*x(x-200)+4800/(x-200)*x(x-200)=-2x(x-200)
Here some of the variable cancel out and the calculations are made and we are left
with the end result which is
4800x-960000+4800x=-2x(x-200)
4800x-960000+4800x=-2x^2+400x (On next step the 2x^2 and the right side is moved to
2x^2-400x+4800x-960000+4800x=0 the left side, hence the change in signs)
2x^2-400x+4800x+4800x-960000=0
Basically at this point my calculations got sketchy because there were several ways of going about this problem at this point, also I believe i had made some errors early in my calculations.
Sorry if it isn't very coherent i did my best to make it so, but I just got LaTex(Tex) and i didnt have the time to learn it just yet, also ms word won't let me paste the equations as they are here without altering them.
Thanks in advance and for bearing with me @_@