SOLUTION: When a popular brand of CD player is priced at $320 per unit, a store sells 12 units per week. Each time the price is reduced by $11, however, the sales increase by 2 per week. Wha

Question 123651This question is from textbook algebra and trigonometry with analiytic geometry
: When a popular brand of CD player is priced at $320 per unit, a store sells 12 units per week. Each time the price is reduced by $11, however, the sales increase by 2 per week. What selling price will result in weekly revenues of $5166?
Please enter your answer as a number without the units. This question is from textbook algebra and trigonometry with analiytic geometry

Answer by edjones(8007) (Show Source): You can put this solution on YOUR website!
price * # of units = revenues.
Let x= # of price reductions
(320-11x)*(12+2x)=5166
-22x^2+508x+3840=5166
-22x^2+508x-1326=0
-11x^2+254x-663=0
x=3, x=20.091
320-11*3= $287. Ans.
.
Check:
(320-11*3)*(12+2*3)
=287*18
=5166
.
The other answer is also correct but the number of price reductions is not even.
The sales price would be $99.
.
Ed

Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)

Quadratic equation (in our case ) has the following solutons:

For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=35344 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: 3, 20.0909090909091. Here's your graph:

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