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AP® Calculus AB · Unit 1 · Topic 1.3

Estimating Limit Values from Graphs: Topic Checklist (Calculus AB 1.3)

Specific “I can…” statements for reading limits from graphs, each linked to the guide section and practice question that shows whether you can do it.

Work through the list without notes or a calculator. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions. This topic is shared by Calculus AB and Calculus BC.

Understanding

  • I can explain what x → a⁻ and x → a⁺ mean, and why the sign shows direction, not whether x is negative. (Guide: “A note on notation”)
  • I can state the rule linking the two one-sided limits to the two-sided limit. (Guide: “One-sided and two-sided limits”; Practice Q5(b))
  • I can explain why the value f(a) does not affect lim (x → a) f(x), using a graph with a hole and a separate dot. (Guide: Worked example 1(a); Practice Q1, Q5(c))
  • I can explain why writing “= ∞” describes a limit that does not exist. (Guide: “A note on writing ∞”; Practice Q6(c))

Skills

  • I can read left-hand and right-hand limits from a graph, including at a jump. (Guide: Worked example 1(b); Practice Q2, Q5(a))
  • I can read a one-sided limit at an endpoint of the domain. (Guide: “One-sided and two-sided limits”; Practice Q5(d))
  • I can recognise a jump, unbounded behaviour and oscillation on a graph, and name which one stops a limit existing. (Guide: “Three ways a limit can fail to exist”; Practice Q3, Q6(a))
  • I can find x-values closer and closer to 0 where an oscillating function takes two different values. (Guide: Figure 2; Practice Q6(b))
  • I can sketch a graph with open and filled circles that matches a list of limit statements. (Practice Q7(a))

Reasoning

  • I can justify “the limit does not exist” by quoting the two one-sided limits, not just by saying “there is a jump”. (Practice Q5(b), Q7(b))
  • I can explain how a graph’s scale or window can hide a hole or a narrow asymptote, and say how I would check. (Guide: Worked example 2; Practice Q4, Q7(d))
  • I can say when my graph reading is only an estimate. (Guide: “What a graph tells you about a limit”)

All ticked? Move on to Estimating Limit Values from Tables, or return to the Calculus AB roadmap or the Calculus BC roadmap.

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