options: Use functions to model relationships between quantities.

Model periodic phenomena with trigonometric functions.

Construct and compare linear and exponential models and solve problems.

Interpret functions that arise in applications in terms of the context.

Prove and apply trigonometric identities.

Interpret expressions for functions in terms of the situation they model.

Analyze functions using different representations.

Define, evaluate, and compare functions.

Build a function that models a relationship between two quantities.

Build new functions from existing functions.

Extend the domain of trigonometric functions using the unit circle.

Understand the concept of a function and use function notation.
problem_activity: Task
Katy is told that the cost of producing $x$ DVDs is given by $C(x) = 1.25x + 2500.$ She is then asked to find an equation for $\frac{C(x)}{x}$, the average cost per DVD of producing $x$ DVDs.
She begins her work: $$\frac{C(x)}{x} =\frac {1.25x+2500}{x}$$ and finishes by simplifying both sides to get: $$C = 1.25+\frac{2500}{x}$$  Is Katy's answer correct? Explain.


correct_option_index: 11