Using Quadratic Formula to solve Quadratic Equations
Ncert Solutions Chapter 4 Quadratic Equations Exercise 4.3 Q8 Download this solution
8. A train travels 360 km at a uniform speed. If, the speed had been 5 km/hr more, it would have taken 1 hour less for the same journey. Find the speed of the train.
Solution:
Let the speed of the train = x km/hr
If, speed had been 5km/hr more, train would have taken 1 hour less. So, according to this condition, we have
Comparing equation
with general equation
, we get
and
Applying quadratic formula
to solve equation, we get
Speed of train cannot be in negative. Therefore, we discard
Therefore, speed of train = 40 km/hr
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