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AP® Calculus AB · Unit 7 · Topic 7.4

Reasoning Using Slope Fields: Topic Checklist (Calculus AB 7.4)

Specific “I can…” statements for reasoning with slope fields, 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 a differential equation usually has a family of solutions, and how one point selects a particular solution. (Guide: “Solutions are functions, and there are many”)
  • I can say how the members of a family are related when dy/dx depends on x only or on y only. (Guide: shifts table; Practice Q4)
  • I can explain why a horizontal line of flat segments is a solution but a sloping line of flat segments is not. (Guide: “Constant solutions”; Practice Q1)

Skills

  • I can find the constant solutions of a differential equation and check them by substitution. (Practice Q1, Q5(c), Q6(a))
  • I can sketch the particular solution through a given point, on both sides of the point. (Guide: “How to sketch a particular solution”; Practice Q5(a))
  • I can find d²y/dx² by implicit differentiation and write it in terms of x and y. (Guide: Worked examples 1 and 2; Practice Q3, Q5(d), Q7(b))
  • I can write a tangent line to a particular solution and use it to estimate a value. (Guide: Worked example 2; Practice Q6(c))

Reasoning

  • I can describe the long-run behaviour of a solution from the field and justify it with the slopes. (Guide: Worked example 1(c); Practice Q2, Q5(b), Q6(d))
  • I can decide whether a tangent-line estimate is an over- or underestimate using concavity. (Guide: Worked example 2(b); Practice Q6(c))
  • I can justify a relative maximum or minimum of a particular solution with dy/dx and d²y/dx². (Practice Q5(d))
  • I can show that a straight line is a solution and reason about whether nearby solutions approach it or move away. (Guide: Worked example 2; Practice Q7)

All ticked? Move on to Topic 7.6, Finding General Solutions Using Separation of Variables, or return to the Calculus AB roadmap or the Calculus BC roadmap.

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