Math Calculus

posted by .

Let C(x) = 0.02x^3 + 55x^2 + 1380.
Find the minimum average cost for this commodity.

I got to the point where I got x=-1374.98, x=-5.018, x=5

but what do I have to do again after this? Because I am missing some steps after I find x.

Do i have to plug all the X's to the original?

thanks :)

  • You have a typo -

    You have a typo. You need a - sign somewhere on the right.

    dC/dx = 0 at min or max

    .02(3)x^2 + 55(2) x = 0
    x (.06 x + 110 ) = 0
    x = 0 or x = - 1833
    0 or a negative number does not makes sense
    Your cost has no minimum in the first quadrant, it goes up forever with number of units.

  • Math Calculus -

    no i don't see any negative sign in my homework question...

    first I did C*bar(x)/x = 0.02x^3+55x^2+1380/(x)
    = 0.02x^2 + 55 x + 1380/x

    then I differentiate it C*bar*'(x) = 0.4x - 1380/x^2 +55

    then I set it equal to zero which gives me x = -137.317 or x=-5.104 and 4.921

    I did the solve function with the calculator

  • Megan ! - Math Calculus -

    Megan, if you look at your original post, there was no division by x at the end
    So Damon was right to question your typing

    C(x) = (0.02x^3 + 55x^2 + 1380)/x
    = .02x^2 + 55x + 1380/x

    C'(x) = .04x + 55 - 1380/x^2
    = 0 for a max/min of C
    .04x^3 + 55x^2 - 1380 = 0

    solving this with my online equation solver I got
    x = 5 and two negative answers

    so x = 5

    plug that back into original C(x)

  • Math Calculus -

    Before you do equals to zero, how did you get 0.04x^3 + 55x^2 - 1380 = 0?

    I set
    0.04x + 55 - 1380/x^2 = 0
    and I got x=-137.317, or x=-5.204,, or x=4.921

    if i plus in to the originals i have to plus each x's?

    and the minimum average is the smallest number from the result after I plug in the Xs?

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Calculus again

    Find the equation of the tangent to y=2-xe^x at the point where x=0 So I found the first derivative by doing the sum rule and product rule. I got e^(x)(x-1) Then I found the slope by substituting 0 for x and got -1. Then I found y …
  2. math

    Jen, I will attempt to write the others out. #3)ADD: -57 + (-22) I got -79 #4)Subtract -2.3-(-8.8) I got -6.5 #7)perform indicated operation: -21 - (-9) I tried to underline ----------- -21 - (-21) I got -12 over o or undfined #8)Multiply:(4){-3/2} …
  3. Calculus

    Could someone work this out so I understand it. Thanks Given the supply function p=S(x)=5(e^0.02x-1) Find the average price (in dollars)over the supply interval [31,36] The 0.02x in the only thing ^ on the e
  4. calculus

    1. (30 points) Consider a manufacturer whose total cost of producing x items is given by c(x)=10000+5x+1/9x^2. a. What is the average cost function A(x)= c(x)/x?
  5. Calculus

    Consider a manufacturer whose total cost of producing x items is given by c(x)=10000+5x+1/9x^2. a. What is the average cost function A(x)= c(x)/x?
  6. Calculus

    Check my work? The equations given were R(x)=-x^2+400x and C(x)=x^2+40x+100. We were asked to find the maximum profit and minimum average cost. (I'm having trouble remembering how to find a minimum and maximum, so please help with
  7. Calculus (Please check my work.)

    This is my last chance to make at least a C in my AP Calculus course, so please tell me if I got these right or wrong so that I can fix them before it's due. Also, there was one I wasn't sure how to do, so if you can help me with that, …
  8. algebra

    A newspaper carrier has $4.00 in change. He has two more quarters than dimes but five times as many nickels as quarters. How many of coins of each type does he have. This is what I got so far and then I get lost. dimes = x quarters …
  9. math/economics in calculus

    The average cost of manufacturing a quantity q of a good, is defined to be a(q) = C(q)/q. The average cost per item to produce q items is given by a(q) = 0.01q2 − 0.6q + 13, for q >0. I know that the total cost is 0.01q^3-0.6q^2+13q …
  10. Economics

    The fixed cost of producing five units of a particular commodity is given as #900 while the total cost of producing the same five units of this commodity is #1000.the marginal cost of the 6th unit produced later is #200.calculate the …

More Similar Questions