SOLUTION: A car traveled the first 100 kilometers of a trip at one speed and the last 135 kilometers at an average of 5 kilometers per hour less. If the entire trip took 5 hours, what was th

Question 1186015: A car traveled the first 100 kilometers of a trip at one speed and the last 135 kilometers at an average of 5 kilometers per hour less. If the entire trip took 5 hours, what was the average speed of the car for the first part of the trip? (Applying quadratic equations)
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!

SPEED TIME DISTANCE first r 100/r 100 last r-5 135/(r-5) 135 SUM 5

In simplifying and solving this equation, a quadratic equation will occur.

-------------------------------THIS BELOW IS WRONG--------------------------------
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SPEED TIME DISTANCE first r 100/r 100 last r-135 135/(r-135) 135 SUM 5

In simplifying and solving this equation, a quadratic equation will occur.
Answer by ikleyn(52787) (Show Source): You can put this solution on YOUR website!
.

The "time" equation is + = 5 hours. (1) The solution can be easily guessed MENTALLY: r = 50 km/h. CHECK. + = 2 + 3 = 5 hours. ! Correct !

Solved.

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Alternatively, you can reduce equation (1) to the standard quadratic equation form
and solve it formally EITHER using the quadratic formula OR by factoring.

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Keep in mind that the setup equation is written INCORRECTLY in the post by @josgarithmetic.

For your safety, IGNORE his post.

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