Question

The highway mileage m in miles per gallon for a compact car is approximated by m(s) = -0.025s2 + 2.45s - 30, where s is the speed in miles per hour. What is the maximum mileage for this compact car to the nearest tenth of a mile per gallon

Answer 1

take the derivative of that function with respect to s, and then set it to zero. Solve for the zero of the derivative and place it on a number line. the numbers to the left of the zero value should be positve and to the right should be negative. This verifies that the zero is a maximum point of that function. Then take that value and sub it back into your mileage equation and you will have you maximum mileage

Answer 2

i got 49 for the maximun speed ijust cant get the max milage i tried every thing i even tried that . :( i got 15mpg . do you have any suggestions or clues on what it could be please?

Answer 3

I got that the speed is -49 and I assume it is a max point, so then you take the -49 and plug it back into the mileage eq and whatever the answer comes out to be is the maximum mileage per gallon.

Answer 4

I think you are on the right path you just don't realize it. I didn't sub it back into the first eq but that is how you're doing it and it seems right on. Maybe check your arithmetic if anything, and maybe the - has something to do with it.