If the speed of a car is increased by 10km/hr, it takes 18min less to cover a distance of 36km then find the speed of the car
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Answered by
69
let the speed of the car be x
time taken to cover 36 km = 36/x hr
ATQ
36/x - 36/(x+10) = 18/60
(36(x+10) - 36x)/x(x+10) = 3/10
(36x + 360 - 36x)/(x^2+ 10x) = 3/10
360x10 = 3(x^2 + 10x)
3x^2 + 30x = 3600
3x^2 + 30x - 3600= 0
x^2 + 10x - 1200=0
x^2 + 40x - 30x - 1200=0
x(x+40) - 30(x+ 40)= 0
(x-30)(x+40)=0
we get 2 answers
But x=30 is the correct one
therefore the speed of the car is 30 km/hr
time taken to cover 36 km = 36/x hr
ATQ
36/x - 36/(x+10) = 18/60
(36(x+10) - 36x)/x(x+10) = 3/10
(36x + 360 - 36x)/(x^2+ 10x) = 3/10
360x10 = 3(x^2 + 10x)
3x^2 + 30x = 3600
3x^2 + 30x - 3600= 0
x^2 + 10x - 1200=0
x^2 + 40x - 30x - 1200=0
x(x+40) - 30(x+ 40)= 0
(x-30)(x+40)=0
we get 2 answers
But x=30 is the correct one
therefore the speed of the car is 30 km/hr
Purushothamreddy:
Super
thanks
I like ur question
I asked another question answer that plz
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