A train travels 360 km at a uniform speed.
If the speed had been 5km/h more it
would have taken 1 hour less for the same
journey. Find the quadratic equation to
find the speed of train.
Answers
Given distance=360 km.
Let the speed of the train be x km/hr.
Speed when increased by 5 km/hr =(x+5) km/hr
x
x360 − (x+5)36 =1
[360x+1800−360x] =1
x(x+5)
x 2
+5x−1800=0
x ² +45x−40x−1800=0
x ²+45x−40x−1800=0
+45x−40x−1800=0x(x+45)−40(x+45)=0
+45x−40x−1800=0x(x+45)−40(x+45)=0(x−40)(x+45)=0
+45x−40x−1800=0x(x+45)−40(x+45)=0(x−40)(x+45)=0x=40,−45
+45x−40x−1800=0x(x+45)−40(x+45)=0(x−40)(x+45)=0x=40,−45The speed of the train is 40 km/hr.
Consider the given question,
Distance =360 km
Speed =x km/hr
When speed is increase (x+5) km/hr
Given expression is written as,
⇒ 360 / x − 360 /(x+5) =1
⇒ ,x+5−x / x(x+5) = 1/ 360
⇒x²+5x=1800
⇒x ² +5x−1800=0
⇒x ² +45x−40x−1800=0
⇒x(x+45)−40(x+45)=0
⇒(x+45)(x−40)=0
⇒x=40,−45
But, speed can not be negative.
Hence, speed is 40 km/h
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