SOLUTION: Rachelle has taken (4x-6)hours to travel 102 km at a speed of (25x+1) kmh^-1. How fast was she traveling?

Question 772331: Rachelle has taken (4x-6)hours to travel 102 km at a speed of (25x+1) kmh^-1. How fast was she traveling?
Answer by KMST(5328) (Show Source): You can put this solution on YOUR website!

THE ALGEBRA WAY:
Since the units agree,
--> --> --> -->
Now we solve that quadratic equation.
Using the quadratic formula, ,
-->-->-->
would give a negative number for the hours driving.
That does not make sense, so we can only use the other solution.
-->-->
So the speed (in km/h) is
The speed is

THE FIFTH GRADER WAY:
If is the speed, must be a small number, maybe 0, or 1, or 2, or 3.
The numbers 0 and 1, give believable speeds, but the time driving turns out negative.
For , , and for ,
Let's try
That makes the speed km/h.
It makes the time hours.
That makes the distance (2 hours) X (51 km/h)= 102 km, so and the speed is
RELATED QUESTIONS
a car travel at a speed of 72 km per hour. The distance, in km, that the car travel in (answered by Alan3354)

1. A motorboat went 70 miles in 4 hours when traveling at full speed upstream on a river... (answered by ewatrrr)

A plane traveling at a constant speed is able to travel 600 miles in 5 hours. How fast... (answered by stanbon)

janet walked to school at 6km/h and rode home from school at a speed of 3 times as fast.... (answered by josgarithmetic)

A BOAT TRAVELING AT A SPEED OF 36 KM PER HOUR. IT HAS TO TRAVEL A DISTANCE OF 210 KM. HOW (answered by Alan3354,PRMath)

It took John 2.5 hours to run from Cinnaminson to Burlington Township at a constant... (answered by jorel1380)

Hi, I`m trying to study some of last years math to keep my mind fresh. I have forgotten... (answered by ramkikk66,MathTherapy)

A motorist traveled from Town A to Town B. After traveling 1/3 of the distance for the... (answered by TimothyLamb)

How long would it take to travel 1 km going at a speed of 100 km/h (answered by robertb)