A train travels at a certain average speed for a distance of 63 km and then travels a distance of 72 km at an average speed of 6 km/h more than its original speed if it takes 3 km to complete the total journey what is the original average speed
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let the original speed of the train be x km/hr
then the increased average speed of train be x+6km/hr
ATQ
=63/x +72/x+6 =3
=63(x+6)+72x/x(x+6) =3
=3x(x+6)=63x+378+72x
=3(x+6)=135x +378
=3x2-117x-378=0
=x2-42x-126(dividing both side by 3)
=x2-42x+3x-126=0
=x(x-42)+3(x-42)
=(x+3)(x+42)
=x=-3 | x=42
so average speed is 42 km/hr.speed can not be negative....
Hope it will help you
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