Rate of Change

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engd846

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Feb 21, 2009
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The question below has 4 choices. I have tried the average rate of change formula and the instantaneous rate of change formula and cannot seem to come up with any of the 4 choices. I do get 1124(C) when I plug 8 in for X, but I think that would be the total cost for 8 wagons, not the marginal cost. Please Help!!!!

The total cost to produce x hand crafted wagons is C(x)=100+8x-Xsquared+2Xcubed. Find the rate of change of the cost with respect to the number of wagons produced(the marginal cost) when x=8.

A) $476 per Wagon
B) $376 per Wagon
C) $1124 per Wagon
D) $1024 per Wagon
 
Did you differentiate your function and then plug in x=8?.

I get one of the choices when doing so.
 
Apparently you have not covered derivatives yet?.

\(\displaystyle C'(x)=6x^{2}-2x+8\)

Now, plug in x=8 and see what you get.
 
If your class and text haven't yet covered derivatives, then you must be expected to find the solution using some other technique. Please reply with that information, showing what you've tried so far.

Please be complete. Thank you! :D
 
engd846 said:
The question below has 4 choices. I have tried the average rate of change formula and the instantaneous rate of change formula and cannot seem to come up with any of the 4 choices. I do get 1124(C) when I plug 8 in for X, but I think that would be the total cost for 8 wagons, not the marginal cost. Please Help!!!!

The total cost to produce x hand crafted wagons is C(x)=100+8x-Xsquared+2Xcubed. Find the rate of change of the cost with respect to the number of wagons produced(the marginal cost) when x=8.

A) $476 per Wagon
B) $376 per Wagon
C) $1124 per Wagon
D) $1024 per Wagon
Click to expand...

What is the definition of marginal cost?

What method/s you have been taught to calculate marginal cost?

What is the instantaneous rate of change formula?

What is the average rate of change formula?
 
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