When a car is moving at x miles per hour...

smileykd

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Sep 27, 2006
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When a car is moving at x miles per hour and the driver slams on the breaks, the car will travel x+(1/20)x^2 feet. If a car travels 175 feet after the driver decides to stop, how fast was the car moving?

I tried setting it up as
.05x^2 + x - 175 = 0
factored as:
(.5x+35)(.1x-5)=0
But then I get two points as an answer, neither of which seems like it could be a speed. Am I setting this up correctly?
 
You're correct. What speeds did you get?. One is negative, one positive.

The positive answer is the good one. It sure looks like it could be a speed to me.
 
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