Sequences and Recurrence Relations

From the study guide

Course Outline

  1. Sequence Notation and Recurrences
  2. Arithmetic Sequences
  3. Arithmetic Sums
  4. Geometric Sequences
  5. Applications of Geometric Growth

1. Sequence Notation and Recurrences

★ Must-know

📌 A sequence can be defined explicitly by a formula such as un=nn+1u_n=\frac{n}{n+1} or recursively by giving initial term(s) and a relation connecting consecutive terms.

  • To calculate successive terms of a recursively defined sequence, start from the given initial term(s), substitute them into the recurrence, and repeat the relation until the requested index is reached.

  • A recurrence model translates a verbal evolution into algebra by identifying the previous value, the next value, and any multiplication, addition, percentage change, or averaging operation between them.

Further detail

  • The recurrence un+1=2un−1u_{n+1}=2u_n-1 with u0=5u_0=5 defines a sequence whose first terms are obtained successively from the preceding term.

Memory Hook

Explicit formula gives a term directly, whereas recurrence builds it from previous terms.

2. Arithmetic Sequences

Key Concepts & Definitions

  • Arithmetic sequence: a sequence for which the same number r, called the common difference, is added to each term to obtain the next term.
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Practice quiz preview

1. Which statement correctly distinguishes an explicit definition from a recursive definition of a sequence?

2. A sequence is defined by u0=5u_0=5 and un+1=2un−1u_{n+1}=2u_n-1. What is u2u_2?

3. Which condition characterizes an arithmetic sequence?

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Flashcard preview

How can a sequence be defined explicitly?

By a formula like un=nn+1u_n=\frac{n}{n+1}.

What is the first step to calculate terms of a recursive sequence?

Start from the given initial term(s).

What defines an arithmetic sequence?

Adding the same number called common difference to each term gives the next term.

What is the explicit formula for an arithmetic sequence with first term u0u_0 and difference rr?

un=u0+rnu_n = u_0 + rn for every natural number nn.

Sequence notation label

Explicit or recursive definition

Arithmetic sequence formula

un+1=un+ru_{n+1} = u_n + r

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Frequently asked questions

What does the Sequences and Recurrence Relations study guide cover?

It covers the core concepts of Sequences and Recurrence Relations, organized by topic with the key definitions, explanations and takeaways, so it's easier to learn and remember.

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How many questions are in the Sequences and Recurrence Relations quiz?

The practice quiz has 9 multiple-choice questions, each with an explanation. Use it to check what you know and find your gaps.

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How do I study Sequences and Recurrence Relations with flashcards?

There are 11 flashcards on Sequences and Recurrence Relations, with a question on the front and the answer on the back. Try to recall each answer before you flip, and let spaced repetition bring back the ones you miss.

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