Question 1073929: A car with good tire tread can stop in less distance than a car with poor tread. The formula for the stopping distance d, in feet, of a car with good tread on dry cement is approximated by
d = 0.04v2 + 0.5v,
where v is the speed of the car. If the driver must be able to stop within 68 ft, what is the maximum safe speed, to the nearest mile per hour, of the car?
...........mph
Answer by jorel1380(3719)   (Show Source):
You can put this solution on YOUR website! If the driver must be able to stop in 68 ft., then the maximum safe speed would be:
68=0.04vē+0.5v
6800=4vē+50v
4vē+50v-6800=0
2vē+25v-3400=0
Using the quadratic formula, we get two roots of 30.584219849 and -55.584219849.
Ignoring the negative answer, we get a maximum safe speed of 30.58 mph. ☺☺☺☺
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