# AS Maths Modelling help please

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#1
A car manufacture uses a model to predict the fuel consumption, y miles per gallon(mpg), for a specific model of car travelling at a speed of x mph.
Y= -0.01x^2 + 0.975x+16, x>0
Question: use the model to find two speeds at which the car has a fuel consumption of 32.5mpg...
THANK YOU
0
4 years ago
#2
Place 32.5 as Y, so you get 32.5= -0.01x^2 + 0.975x+16, x>0,
Make it a quadratic equation so one side = 0, and solve using the quadratic formula.
2
#3
(Original post by Maxiimoose)
Place 32.5 as Y, so you get 32.5= -0.01x^2 + 0.975x+16, x>0,
Make it a quadratic equation so one side = 0, and solve using the quadratic formula.
Yay thanks
0
4 weeks ago
#4
i did that, and solved by the formula, bu t got -13.75 and 111.25, both of which are wrong.( correct answers are 28.1 and 75.7)can you please help me with finding out what i did wrong?
0
4 weeks ago
#5
This thread is 3 years old and I have no idea what is about it but, from what your answers are you put the numbers incorrectly into the formula
0
4 weeks ago
#6
(Original post by Maxiimoose)
This thread is 3 years old and I have no idea what is about it but, from what your answers are you put the numbers incorrectly into the formula
yeah, i had forgotten to place a negative sign.

Its funny how one sign can make such a difference.

thanks anyways though.
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