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AP® Calculus AB · Unit 3 · Topic 3.2

Implicit Differentiation: Topic Checklist (Calculus AB 3.2)

Specific “I can…” statements for implicit differentiation, 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 why d/dx [y³] is 3y² · dy/dx, using the chain rule with y as the inner function. (Guide: “The key idea”; Practice Q1)
  • I can explain why an implicit dy/dx usually contains y, using two points on a curve with the same x. (Guide: Figure 1)
  • I can say what a zero numerator and a zero denominator in dy/dx tell me about the tangent line. (Guide: “Horizontal and vertical tangent lines”; Practice Q3)

Skills

  • I can differentiate y terms such as yⁿ, sin y, e^y and ln y with respect to x. (Guide: table in “The key idea”; Practice Q1, Q4)
  • I can use the product rule on terms such as xy and x²y, keeping both terms. (Guide: Worked example 1; Practice Q2, Q5)
  • I can collect the dy/dx terms, factor and divide to make dy/dx the subject. (Guide: “The method in five steps”; Practice Q5(b), Q6(a))
  • I can check a point is on the curve, evaluate dy/dx with both coordinates and write the tangent line. (Guide: Worked examples 1 and 3; Practice Q5(c), Q7(b))
  • I can find all points with horizontal or vertical tangents by solving with the curve’s equation. (Guide: Worked example 2; Practice Q6)

Reasoning

  • I can reject a candidate point that is not on the curve, or one where the denominator of dy/dx is 0 instead of the numerator. (Guide: “Horizontal and vertical tangent lines”; Practice Q3)
  • I can argue from the sign of each term that a denominator is never 0, so there is no vertical tangent. (Practice Q7(c))
  • I can spot a missing dy/dx, a missing product-rule term or a constant wrongly differentiated in someone else’s work. (Guide: “Common misconceptions”; Practice Q2)

All ticked? Move on to Topic 3.3, Differentiating Inverse Functions, or return to the Calculus AB roadmap or the Calculus BC roadmap.

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