SOLUTION: An airplane travels 400km at a certain speed. One year later, the same airplane does the same trip at a speed 50km/hr faster than a year ago, and it takes one hour less time. What

Question 415647: An airplane travels 400km at a certain speed. One year later, the same airplane does the same trip at a speed 50km/hr faster than a year ago, and it takes one hour less time. What was the speed of the airplane one year ago
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
speed x
speed x+50 after one year

Distance = same 400km
original time � time with increased speed =1hour
t=d/t
400/x-400/(x+400 )=1
LCD= (x+ 400)
multiply by LCD
400(x+400)-400x =x(x+400 )
400x+160000-400x =1X^2+400x
160000=X^2+400x
X^2+400x-160000 =0
solve using quadratic formula
a= 1 , b = 400 , c ==-160000 .
b^2-4ac=800000

x1= 247.21
x2 is negative so ignore
original speed = 247.21 mph
after one year speed= 297.21 mph
...

RELATED QUESTIONS
An Airplane travels in 5hrs. with a speed of 50km/hr. How far does it travel? (answered by nerdybill)

Airplane A travels 1000 mi at a certain speed. Airplaine B travels the same distance in 1 (answered by mananth)

Airplane A travels 2800 km at a certain speed. Airplane B travels 2000 km at a speed 50... (answered by ptaylor)

An airplane travels 1400 miles in the same amount of time it takes a car to travel 210... (answered by stanbon)

Airplane A travels 1400km at a certain speed. Plane B travels 1000km at a speed 50 km/h... (answered by ankor@dixie-net.com)

An airplane travels a total distance of 5,585 kilometers on a trip. It travels 563... (answered by josgarithmetic,MathTherapy)

one airplane travelling at 500 miles per hour, a second airplane leaves 30 minutes later... (answered by Alan3354)

Airplane A travels 2800 km at a certain speed. Plane B travels 2000 km at a speed 50... (answered by Fombitz)

Emily travels in an airplane a distance of 2880 km. For one-third of the distance, the... (answered by ikleyn)