Question

(4) When there is a decrease of 10 km/h in the usual speed of a train, it takes 4, hours more to cover 900 km. We need to find the usual speed of the train. solve this equations in quadratic equations ​

Answer 1

Answer:

distance = speed * time

Step-by-step explanation:

given

time taken difference is 4 hours

time taken by usual speed - time taken when speed decreases = 4 hours

let usual speed be x km/hr

time usual = distance / speed

= 900 / x

time when decreased = distance / speed

= 900 / (x - 10)

T usual - T decreased = 4 hours

900/x - 900/x-10 = 4

900 ( 1/x - (1/x-10) ) = 4

4 * x(x - 10) = 900 * (-10)

x2 - 10x + 2250 = 0

x = 5 + 5 root 89