Question

The highway mileage m in miles per gallon for a compact car is approximated by m(s) = -0.025s^2 + 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? __________ mi/gal.

Answer 1

x value of the vertex= -a/2b

inverse of that -b/2a = -2.45/2(-0.025)= 49 plug in 49 for S

Answer 2

Do I square s first?

Answer 3

yes

Answer 4

Well, I got 30.025 but it said it was wrong. Is that right? Or did I do something wrong?

Answer 5

it just 30 cuz you're only worried about to the 1/10 of the mile

Answer 6

Oh okay, thank you! So do you know how I could figure out the speed that results from this mileage?

Answer 7

And 30 isn't right either :(

Answer 8

do u have idea about derivation.

Answer 9

No, I don't think so.

Answer 10

can u convert it into completed square form

Answer 11

-0.025s^2 + 2.45s - 3

Answer 12

m(s) = -0.025s^2 + 2.45s - 30
=-0.025(s^2-98s)-30
=-0.025{s^2 - 2 * s * 49 + 49^2 -49^2)-30
=-0.025{(s-49)^2 -2401}-30
=-0.025(s-49)^2 + 60.025-30
=-0.025(s-49)^2+30.025

Answer 13

for all real values of s,