Question

The time taken by a person to cover 150 km was 2whole 1 / 2 hrs more than the time taken in the return journey. If he returned at speed of 10 km / hr more than the speed while going. Find the speed per hr in each direction.


Class 10


Quadratic Equation

Answer 1

Forward speed x
return speed x + 10

Distance = same 150 miles 1
original time – time with increased speed = 2.5 hour
t=d/t

150 / x - 150 / ( x + 10 ) = 2.50
LCD= x ( x + 10 )
multiply by LCD
150 ( x + 10 ) - 150 x = 2.5 x ( x + 10 )
150 x + 1500 - 150 x = 2.5 X^2 + 25 x
1500 = 2.5 X^2 + 25 x


2.5 X^2 + 25 x - -1500 = 0
Find roots of the quadratic equation
a= 2.5 b= 25 c= -1500

x1= ( -25 + sqrt( 625 + 15000 )) / 5
x1=( -25 + 125 )/ 5
x1= 20

x2= ( -7 - sqrt( 49 - 20 ) / 2
x2=( -25 - 125 )/ 5
x2= -30
Ignore negative
forward speed = 20 kmph
return speed = 30 kmph

Answer 2

hey mate.
here's the solution