RecycledCDs, Incorporated, offers a choice of 5 used CDs for $23, With each additional CD costing $7. Write a cost function for purchasing 5 or more CDs. What will the cost of buying 12 CDs be? Let x represent the number of CDs over 5.

-- Cost Function

Cost of buying 12CDs is $72

Step-by-step explanation:

Given

Solving (a): Cost Function

Let n represent CDs greater than 5

Substitute:

  and    

Open Bracket

Collect Like Terms

Solving (b): When n = 12

Substitute 12 for n in

Cost of buying 12 CDs is $72

- 1.613 = -1.6 or -1.61

-1.522 = -1.5 or -1.52

0.587 = 0.6 or 0.59

3.079 = 3.1 or 3.08

i did it myself and i got 4.2 (b) hope its right

step-by-step explanation: