The sales of a particular CD can be modeled by the equation , where S is the number of CDs sold in thousands and m is the number of months.

The value of substitute in the equation, .

Factor by using the GCF.

Apply zero product property: .

Solve the first equation, .

Solve the second equation, .

So, they will stop in month 5.

The peak will occur halfway between 0 and 5 or 2.5.

The peak amount is .

Since S is the number of CDs sold in thousands

.

(a)They will stop in month 5.

(b)The peak will occur halfway between 0 and 5 or 2.5.

(c)The number of CDs is .