options: Understand the concept of a function and use function notation.

Analyze functions using different representations.

Define, evaluate, and compare functions.

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

Construct and compare linear and exponential models and solve problems.

Use functions to model relationships between quantities.

Build new functions from existing functions.

Build a function that models a relationship between two quantities.

Prove and apply trigonometric identities.

Model periodic phenomena with trigonometric functions.

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

Extend the domain of trigonometric functions using the unit circle.
problem_activity: Task
At the beginning of January, Susita had some money in her checking account.  At the end of each month she deposits enough to double the amount currently in the account. However, she has a loan to pay off, requiring her to withdraw \$10 from the account monthly (immediately after her deposit).
Assuming January is the first month, write an equation that describes the amount of money in Susita’s account at the end of the $n^{\rm th}$ month, $S(n)$, in terms of the amount of money in Susita’s account at the end of the $(n-1)^{\rm th}$ month, $S(n-1)$.
At the end of May, Susita had \$2 left in the account.  How much did she have at the end of January?


correct_option_index: 7