Exam Strategy
Pre-calculus · AP · Polynomial and Rational Functions
CED focus
Rational Functions and Vertical Asymptotes
This topic is assessed on the AP Exam.
Multiple-choice tips
- Ask whether the limit is one-sided, two-sided, or DNE before computing.
- Factor or rewrite before choosing a limit or asymptote answer.
- Eliminate MC choices that ignore holes vs vertical asymptotes.
- Check end behavior signs from leading terms, not only a calculator window.
- On rational items, test whether cancellation changes the graph (removable discontinuity).
Free-response tips
- Use ‘approaches’ language; cite IVT or continuity when justifying.
- State domain restrictions and asymptote locations before graphing.
- Show factoring or long division that reveals holes and end behavior.
- Label intercepts and asymptotes on a sketch; connect to the equation.
- Interpret zeros and asymptotes in context when the stem is applied.
Common traps
- Equating lim f(x) as x→a with f(a) when a hole exists
- Treating every canceled factor as an asymptote instead of a hole
- Confusing far-left/far-right behavior with local max/min
- Using a calculator graph without stating algebraic end behavior
Quick checklist
- [ ] Can state domain and asymptote locations for one rational example
- [ ] Can factor or divide to expose a hole
- [ ] Can explain end behavior from leading terms