Back to Series approximations

Series expansions and small-angle approximations topic check

Practise series expansions and small-angle approximations in H2 Mathematics, check independently, and return later to review. This check covers selected skills, not the whole course topic.

Learning goals
  • Expand by substitution into standard series and state where the standard expansions are valid
  • Find leading Maclaurin terms of products, quotients and compositions of standard series
  • Find leading Maclaurin terms of an implicitly defined function from its relation and value at zero
  • Use small-angle approximations to give a quadratic approximation of a trigonometric expression
  • GCE A-Level H2 Mathematics 2027
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Expand standard series and state validity · Check your progress

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Use small-angle approximations · Check your progress

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Combine series in products and compositions · Check your progress

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Find series from implicit relations · Check your progress

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Check again

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Expand standard series and state validity · Check again

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Use small-angle approximations · Check again

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Combine series in products and compositions · Check again

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Find series from implicit relations · Check again

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Retention check

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Expand standard series and state validity · Retention check

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Use small-angle approximations · Retention check

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Combine series in products and compositions · Retention check

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Find series from implicit relations · Retention check

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Practise: Expand standard series and state validity

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Practise: Use small-angle approximations

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Practise: Combine series in products and compositions

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Practise: Find series from implicit relations

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Revision notes

Revise series approximations

Choose valid local expansions, derive composite and implicit coefficients, and check the accuracy of truncated approximations.

Key ideas

  1. Standard series and convergence

    Choose standard expansions with their transformed intervals, then distinguish convergence, domain and useful numerical accuracy.

  2. Composite and implicit series

    Combine series through a chosen order, derive local coefficients by repeated differentiation, and verify implicit approximations.

What the syllabus asks

From the GCE A-Level H2 Mathematics 2027 syllabus

  • Include: standard expansions of (1 + x)^n for rational n, e^x, sin x, cos x and ln(1 + x); first few terms by repeated differentiation (e.g. sec x), repeated implicit differentiation (e.g. y³ + y² + y = x² − 2x), or standard series (e.g. e^x cos 2x, ln((1 + x)/(1 − x))); convergence ranges; approximation of a function; small-angle approximations sin x ≈ x, cos x ≈ 1 − x²/2, tan x ≈ x. Exclude derivation of a general term.