a train travells a distance of 300km in uniform speed. if it's speed decreases to 5km/h it would have taken 2hours more to cover same distance. find the speed of the train
Answers
Answer:
Step-by-step explanation:
Let the speed of the train X km/h
Distance =300km
According to question uniform speed be
T1= D/S = 300/X
when speed decrease 5 km/h
T2 = 300/x-5
According to question-----
T2 - T1 =2
(300/x-5) - (300/x) =2
= 2x^2 - 10x - 1500 =0
D=b^2 -4AC
=(-10)^2 - 4(2) (-1500)
√D =√12100
= 110
Alpha is equal to minus b + rootD divided by 2 and beta is equal to minus b minus root D divided by 2. But Beta is equal to negative so beta can't be considered
X=(10+110) /4 =30Km/h
so the speed of the train be 30km/h
Answer:
Step-by-step explanation:
Let the speed of the train be x
Case1
D=300km S1= x km/h
S=D/T
T1=D/S1
T1=300/x (I)
Case2
D=300 S2=x-5km/h
T2=D/S2
T2=300/x-5
ATQ
T2-T1=2hrs
300/x-5-300/x=2
300 (1/x-5-1/x)=2
300 (x-x+5)/x(x-5)=2
300 (5)/x^2-5x=2
1500=2x^2-10x
2x^2-10x-1500=0
x^2-5x-750=0
x^2-30x+25x-750=0
x(x-30)+25 (x-30)=0
(x+25)(x-30)=0
x=-25 x=30
Speed of the train=30km/h