SOLUTION: The gas mileage g (measured in mi/gal) for a particular vehicle, driven at v mi/h, is given by the formula g=10+0.9v-0.01v^2, as long as v is between 10 mi/h and 75 mi/h. For what

Question 495245: The gas mileage g (measured in mi/gal) for a particular vehicle, driven at v mi/h, is given by the formula g=10+0.9v-0.01v^2, as long as v is between 10 mi/h and 75 mi/h. For what range of speeds is the vehicle's mileage 30 mi/gal or better?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Solve: 10+0.9v-0.01v^2 >= 30
Rearrange:
0.01v^2 - 0.9v + 20 <= 0
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Multiply thru by 100:
v^2 - 90v + 2000 <= 0
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Solve the Equality:
(v-50)(v+40) = 0
Positive solution:
v = 50
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Complete solution v <= 50
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Cheers,
Stan H.
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