Question

Hey frnds pls answer me !! A car takes two hours less for a journey of 300 km,if its speed is increased by 5 km/ hr from its usual speed.Find usual speed

Answer 1

Hola Friend ✋✋✋

Let the usual speed be ' x '

Time = Distance/ speed

Given

t = 300/x

if speed is increased

t - 2 = 300 / ( x + 5 )

so....

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

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

(300x + 1500 - 300x) = 2x² + 10x

x² + 5x - 750 = 0

x = -5 ± √(3025) / 2

x = - 5 ± 55/2

x = -30, 25

Speed won't come in negative.... so usual speed is 25 km/h

Hope you will understand

Answer 2

Answer:

Time= distance/speed

let unusual speed be x

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

300{(x+5)-x}=2(x+5)x

1500=2x(x+5)

x(x+5)=750

(x^2)+5x-750=0

from this equation, we can find the two zeroes for the equation as -30 and 25

as speed can never be negative,

so x=25 kmph