A TRAIN COVERS A DISTANCE OF 90 KM AT A UNIFORM SPEED.HAD THE SPEED BEEN 15 KM PER HOUR MORE,IT WOULD HAVE TAKEN HALF AN HOUR LESS FOR THE JOURNEY.FIND THEORIGINAL SPEED OF THE TRAIN.
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let original speed of train is x km/h and t is right time in hour
now according to question
90/x=t -------------(1)
90/(x+15)=t-30/60 -----------------(2)
subtracting (1) to (2)
now
90 {15/(x^2+15x)=1/2
x^2+15x-2700=0
use quadratic formula
x=45km/h
hence original speed of train =45km/h
now according to question
90/x=t -------------(1)
90/(x+15)=t-30/60 -----------------(2)
subtracting (1) to (2)
now
90 {15/(x^2+15x)=1/2
x^2+15x-2700=0
use quadratic formula
x=45km/h
hence original speed of train =45km/h
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