A train travels 360km at a uniform speed. if the speed had been 5km/j more, it would have taken 1 hour less for the same journey. find the speed of the train
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1
speed of train is 40km/h then it takes 9hrs
when speed is x+5 that is 45km/h then it takes 8hrs
when speed is x+5 that is 45km/h then it takes 8hrs
Answered by
7
Let..,
Speed be v
Time be T
Speed = Distance / Time
Distance = Speed * Time
360 = vT ——(1)
According to question
360 = (v + 5)*(T - 1)
From equation (1) 360 = vT
vT = (v + 5)(T - 1)
vT = v(T - 1) + 5(T - 1)
vT = vT - v + 5T - 5
v = 5T - 5
From equation (1) T = 360/v
v = 5*360/v - 5
v - 1800/v = - 5
v^2 - 1800 = -5v
v^2 + 5v - 1800 = 0
Solve this polynomial equation
We will get v = 40km/h and v = -45km/h
Speed can’t be be negative.
Therefore speed of train is 40km/h
Speed be v
Time be T
Speed = Distance / Time
Distance = Speed * Time
360 = vT ——(1)
According to question
360 = (v + 5)*(T - 1)
From equation (1) 360 = vT
vT = (v + 5)(T - 1)
vT = v(T - 1) + 5(T - 1)
vT = vT - v + 5T - 5
v = 5T - 5
From equation (1) T = 360/v
v = 5*360/v - 5
v - 1800/v = - 5
v^2 - 1800 = -5v
v^2 + 5v - 1800 = 0
Solve this polynomial equation
We will get v = 40km/h and v = -45km/h
Speed can’t be be negative.
Therefore speed of train is 40km/h
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