Sequences As Functions, Example 3

Sequences As Functions, Example 3
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2019-08-22 22:13
This example demonstrates how to find the ninth term in a sequence defined by the formula a_n = 3n + 1. It covers the relationship between sequences and functions. Key GeoGebra commands and objects used include LaTeX, Corner, If, Sequence, TableText, Max, Min, stepMax, stepper, steps, counter, text0, RandomizationText, Original, Randomize, button1, topright, bottomleft, heightToWidth, button2, xscale, yscale, coef, const, and objects B1 to B10. Suitable for middle school and above, focusing on sequence-function conversion and computation.

GeoGebra Commands & Parameters

  1. LaTeX(steps) → counter
  2. LaTeX("\text{Move the slider to solve the problem.}") → text0
  3. LaTeX("\text{Use the buttons below to return to the original}\cr\text{problem or randomly generate a similar practice}\cr\text{problem.}") → RandomizationText
  4. Corner(2, 3) → topright
  5. Corner(2, 1) → bottomleft
  6. If(const > 0, "+", "-") → constSign
  7. If(choose ≟ 0, LaTeX[(((("a_n=" * coef) * "n") * constSign) * absConst)], LaTeX[(((((("a_n=" * coef) * "a_{n-1}") * constSign) * absConst) * "\text{ and }a_0=") * const)]) → formula
  8. If(choose ≟ 0, explicit, recursive) → sequenceVals
  9. Sequence((n(j), sequenceVals(j)), j, 1, graphterms) → plotPoints
  10. LaTeX("\text{Determine whether this is an explicit formula or a}\cr\text{recursive formula.}") → text1
  11. LaTeX((((((("\text{Find and graph the first " * graphterms) * " terms, starting with }\textcolor{#000099}{n=1}\text{,}\cr\text{of the sequence given by the formula }\cr\textcolor{#000099}{") * formula) * "}\text{,}\cr\text{where }\textcolor{#000099}{a_n}\text{ is the value of the term and }\textcolor{#000099}{n}\text{ is the term}\cr\text{number. Then find the ") * finalterm) * "th term.}")) → Problem
  12. If(choose ≟ 0, LaTeX["\text{This is an explicit formula because the right hand}\cr\text{side depends only on }\textcolor{#000099}{n}\text{ and not on }\textcolor{#000099}{a_{n-1}}\text{ or similar}\cr\text{terms.}"], LaTeX["\text{This is a recursive formula because the right hand}\cr\text{side depends on }\textcolor{#000099}{a_{n-1}}\text{ and we are given an initial}\cr\text{term, }\textcolor{#000099}{a_0}\text{.}"]) → text2
  13. LaTeX((("\text{Find the first " * graphterms) * " terms of the sequence.}")) → text3
  14. If(choose ≟ 0, Sequence[LaTeX[(((((((((("a_" * k) * "=") * coef) * "(") * k) * ")") * constSign) * absConst) * "=") * sequenceVals(k))], k, 1, graphterms], Append[LaTeX[(((((((("a_1=" * coef) * "(") * const) * ")") * constSign) * absConst) * "=") * sequenceVals(1))], Sequence[LaTeX[(((((((((("a_" * k) * "=") * coef) * "(") * sequenceVals(k - 1)) * ")") * constSign) * absConst) * "=") * sequenceVals(k))], k, 2, graphterms]]) → firstTerms
  15. LaTeX((("\text{Substitute the respective values for }\textcolor{#000099}{n=1}\text{ through }\cr\textcolor{#000099}{n=" * graphterms) * "}\text{.}")) → text4
  16. LaTeX(formula) → text4b
  17. TableText({firstTerms}, "v") → text4c
  18. Sequence(sequenceVals(k), k, 1, graphterms - 1) → shortList
  19. LaTeX("\text{Create ordered pairs from the sequence.}") → text5
  20. LaTeX("\text{The first coordinate is }\textcolor{#000099}{n}\text{ and the second coordinate}\cr\text{is }\textcolor{#000099}{a_n}\text{.}") → text6
  21. LaTeX("\text{Plot the ordered pairs.}") → text8
  22. LaTeX((("\text{Find the " * finalterm) * "th term in the sequence.}")) → text9
  23. If(choose ≟ 0, LaTeX[(((("\text{Since the sequence is explicitly defined, evaluate}\cr\text{the formula, }\textcolor{#000099}{" * formula) * "}\text{ at }\textcolor{#000099}{n=") * finalterm) * "}\text{.}")], LaTeX[(("\text{Since the sequence is recursively defined, continue}\cr\text{building up to the " * finalterm) * "th term one term at a time.}")]) → text10a
  24. Sequence(sequenceVals(k), k, 1, graphterms) → graphedList
  25. Max(0, Max[graphedList]) → maxy
  26. Sequence(LaTeX[(((((((((("a_" * k) * "=") * coef) * "(") * sequenceVals(k - 1)) * ")") * constSign) * absConst) * "=") * sequenceVals(k))], k, graphterms + 1, finalterm) → moreTerms
  27. If(choose ≟ 0, LaTeX[(((((((((("a_" * finalterm) * "=") * coef) * "(") * finalterm) * ")") * constSign) * const) * "=") * sequenceVals(finalterm))], TableText[{moreTerms}, "v"]) → text10b
  28. LaTeX((((("\text{The " * finalterm) * "th term in the sequence is ") * sequenceVals(finalterm)) * ".}")) → text10c
  29. LaTeX((((((("\text{" * text10a) * "}\cr\textcolor{#000099}{") * text10b) * "}\cr\text{") * text10c) * "}")) → text10
  30. LaTeX((((((("\text{The first " * graphterms) * " values are ") * shortList) * "}\cr\text{and ") * sequenceVals(graphterms)) * ".}")) → text4d
  31. TableText({Append[LaTeX["(n,a_n)"], plotPoints]}, "v") → text7
  32. Min(0, Min[graphedList]) → miny

AI Drawing Prompt Reference

Create a graph showing the function a_n = 3n + 1 and its sequence points. Include a slider to calculate and display the first few terms of the sequence, highlighting the 9th term. Plot the sequence points and compare them with the function graph. Label key information like sequence values, the function formula, and the 9th term result, noting that it's an explicit formula.
The prompt above was compiled from the original drawing commands and is for reference only.