# Marginal cost- i've never done these types of problems before and very confused

jtt

## Homework Statement

suppose that the dollar cost of producing x washing machines is c(x)= 2000 + 100x-0.1x6^2

a) find the average cost of producing 100 washing machines.
b) find the marginal cost when 100 washing machines are produced.

## Homework Equations

c(x)= 2000 + 100x-0.1x6^2: the only equation given

## The Attempt at a Solution

i've tried taking the derivative and then substituting it with 100. for part a and for part b i didnt take the derivative, just plugged in 100 into the equation given

Homework Helper
Could you clarify that cost function expression? Is it $c(x) = 2000 + 100x - 0.1x^{2}$?

The total cost to produce 100 washing machines is c(100) . The average cost is the cost per machine, which is $\frac{ c(100) }{100} .$

The marginal cost, on the other hand, is the linearization for finding the amount of additional cost it would take to produce one more machine, given that 100 have already been built. This linearization is $c'(100) \cdot ( 101 - 100 )$ , or just c'(100) .

jtt
yes the cost function expression is c(x)= 2000 + 100x-0.1x^2

Homework Helper
Well, the definitions I've given are all you need. You started doing some calculations along those lines, but I think you had some of what you needed to do swapped relative to which part it goes with.

jtt
thanks for the help on this