Question

A train takes 2 hours less for a journey of 300km if its speed is increased by 5km/hr from its usual speed find the usual speed of the train ​

Answer 1

Solution==>>

Let x = normal speed

300 / (x + 5) + 2 = 300 / x

. . . combine left side into a single fraction

(310 + 2x) / (x + 5) = 300 / x

. . . cross multiply

310x + 2x^2 = 300x + 1500

2x^2 + 10x - 1500 = 0

x^2 + 5x - 750 = 0

(x - 25) (x + 30) = 0

x = -30 <== invalid negative time

x = 25 km / h <===== answer

Answer 2

Answer:

Step-by-step explanation:

let the usual speed of the train to be 'x' km/hr

ACCORDING TO THE QUESTION-

300/x -- 300/x+5 = 2

by solving this equation , we get,

1/x - 1/x+5 = 1/150

therefore, the equation becomes,

x²+5x-750=0

now, solving by method of factorization,

x²+30x-25x-750=0

x(x+30)- 25(x+30)=0

(x-25)=0

x= 25

(x+30)=0

x= -30

but, speed of train can't be in negative, so we will reject the value in minus sign.

therefore, x= 25

therefore, USUAL SPEED OF TRAIN= 25 km/hr...... ANSWER