Learn on PengiAoPS: Introduction to Algebra (AMC 8 & 10)Chapter 22: Special Manipulations

Lesson 2: Self-similarity

Property.

Section 1

Identify self-similarity in infinite expressions

Property

An infinite expression exhibits self-similarity when a portion of the expression is identical to the entire expression. This creates a pattern where the same structure repeats within itself indefinitely.

Examples

Section 2

Recognize infinite patterns using ellipsis notation

Property

Ellipsis notation uses three dots (\ldots) to indicate that a pattern continues infinitely. In self-similar expressions, the pattern repeats the same structure at every level.

Examples

Section 3

Setting up equations from self-similar expressions

Property

To set up an equation from an infinite self-similar expression, let the entire expression equal a variable xx, then identify the self-similar portion within the expression that also equals xx.

For nested radicals: x=a+a+a+x = \sqrt{a + \sqrt{a + \sqrt{a + \cdots}}} becomes x=a+xx = \sqrt{a + x}

Section 4

Substitution method for self-similar expressions

Property

To solve self-similar expressions using substitution:

  1. Identify the self-similar part of the expression that appears within itself.

Book overview

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Continue this chapter

Chapter 22: Special Manipulations

  1. Lesson 1

    Lesson 1: Raising Equations to Powers

  2. Lesson 2Current

    Lesson 2: Self-similarity

  3. Lesson 3

    Lesson 3: Symmetry

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Identify self-similarity in infinite expressions

Property

An infinite expression exhibits self-similarity when a portion of the expression is identical to the entire expression. This creates a pattern where the same structure repeats within itself indefinitely.

Examples

Section 2

Recognize infinite patterns using ellipsis notation

Property

Ellipsis notation uses three dots (\ldots) to indicate that a pattern continues infinitely. In self-similar expressions, the pattern repeats the same structure at every level.

Examples

Section 3

Setting up equations from self-similar expressions

Property

To set up an equation from an infinite self-similar expression, let the entire expression equal a variable xx, then identify the self-similar portion within the expression that also equals xx.

For nested radicals: x=a+a+a+x = \sqrt{a + \sqrt{a + \sqrt{a + \cdots}}} becomes x=a+xx = \sqrt{a + x}

Section 4

Substitution method for self-similar expressions

Property

To solve self-similar expressions using substitution:

  1. Identify the self-similar part of the expression that appears within itself.

Book overview

Jump across lessons in the current chapter without opening the full course modal.

Continue this chapter

Chapter 22: Special Manipulations

  1. Lesson 1

    Lesson 1: Raising Equations to Powers

  2. Lesson 2Current

    Lesson 2: Self-similarity

  3. Lesson 3

    Lesson 3: Symmetry