Recycled CDs, Incorporated, offers a choice of 5 used CDS for $20, with each additional CD costing $4. Write a cost function for purchasing 5 or more CDs. What will the cost of buying 13 CDs be? Let x represent the number of CDs over 5.

C(x) = _____

Please help asap! This is due today and I feel confused. Tysm!


  1. The the cost of 13 CDs would be $30.

    How to find the Cost Function?

    A cost function is a function of input prices and output quantity whose value is the cost of making that output given those input prices, often applied through the use of the cost curve by companies to minimize cost and maximize production efficiency.
    If $20 represents the cost of  the 5 used CDs, than your formula would be “20 + 4x” , with x being the amount of extra CDs you purchase.
    The number of CDs minus 5 is our x value, because the first 5 are the used CDs bundled into the $20 group. Thus;
    26 + 4(13 – 5)
    26 + 4(1)
    26 + 4 = $30
    Thus, we conclude that the cost of 13 CDs would be $30
    Read more about Cost Functions at;


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