P3

Geometric Sequence

等比数列

Pattern / 模式识别
Grades G4 - G7
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What It Looks Like

Recognition signals — when you see these, think of this structure:

  • 1A sequence where terms grow or shrink rapidly
  • 2Numbers that look like they're being multiplied by the same factor
  • 3Words like 'doubles each time' or 'halves each stage'
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What It Really Tests

The core mathematical idea behind this structure:

Each term is obtained by multiplying the previous term by a constant ratio.

每一项都是前一项乘以固定比值。

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Why Students Get Stuck

Common mistakes to watch out for:

  • Assuming it's a linear pattern and checking differences
  • Only testing the first two terms and not verifying the pattern continues
  • Confusing multiplication with exponentiation
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Your First Step

How to begin thinking about problems with this structure:

Compute the ratio between consecutive terms: divide each term by the one before it.

计算相邻项的比值:用每一项除以前一项。

Related Structures

These structures share similar patterns or thinking approaches: