Q31 of 805 Page 1

A train travels 180 km at a uniform speed. If the speed had been 9 km/hour more, it would have taken 1 hour less for the same journey. Find the speed of the train.

OR


Find the roots of the equation .


Let, the distance covered by the train = d km

Speed of the train = s km/hour


And the time taken by the train = t hour


180 = s × t …(1)


180 = (s + 9) × (t – 1) ⇒ …(2)


From eq.(1) and eq.(2)



180s + 1620 = 189s + s2


s2 + 9s – 1620 = 0


(s – 36)(s + 45) = 0


s = 36 and -45


But, speed of train is neither be negative.


So, speed of train is 36 km/hour.


OR



⇒


⇒ 3x – 8 = 2x2 – 13x + 15


⇒ 2x2 – 16x + 23 = 0


⇒


⇒


⇒


⇒ and


So, the roots of the equation are and


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