STEP 2015: 21 of 26 questions decoded, by method & chapter.

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The paper at a glance, coloured by move. Click a square to open its question; empty squares are not decoded yet.

• 1Sandwiching Sums with IntegralsKey methodPureSequences & Series4 other sittings

  Same method, other sittings

  2009201220142017

  Worked solutionOpen the method
• 2The Chebyshev BridgeKey methodPureTrigonometry1 other sitting

  Same method, other sittings

  2011

  Worked solutionOpen the method
• 3Induction with an InvariantKey methodPureProof & Number Theory2 other sittings

  Same method, other sittings

  20062018

  Worked solutionOpen the method
• 4Symmetry → Turning PointsKey methodPureFunctions & Curve Sketching3 other sittings

  Same method, other sittings

  200920122013

  Worked solutionOpen the method
• 5Telescoping SumsKey methodPureSequences & Series6 other sittings

  Same method, other sittings

  201220142016201720222024

  Worked solutionOpen the method
• 6Reflect the Interval & AddKey methodPureIntegration6 other sittings

  Same method, other sittings

  200620102016201820202022

  Worked solutionOpen the method
• 7Quadratic → DiscriminantDifference of Two SquaresCompleting the SquareKey methodPureCoordinate Geometry & Conics6 other sittings

  Same method, other sittings

  200920122017201820242025

  Worked solutionOpen the method

  AlsoDifference of Two SquaresCompleting the Square
• 8Affine Combinations & the Section FormulaKey methodPureVectors & Matrices6 other sittings

  Same method, other sittings

  200620082009201220142024

  Worked solutionOpen the method
• 9Moment of Inertia → RotationTunnelMechanics5 other sittings

  Same method, other sittings

  20062008201220132018

  Worked solutionOpen the method
• 11Kinematic ConstraintsKey methodMechanics3 other sittings

  Same method, other sittings

  200820142023

  Worked solutionOpen the method
• 12First Step → Self-Referential EquationKey methodProb & StatsProbability & Statistics4 other sittings

  Same method, other sittings

  2011201420202021

  Worked solutionOpen the method
• 13Optimise Expected Cost or GainKey methodProb & StatsProbability & Statistics3 other sittings

  Same method, other sittings

  200920182022

  Worked solutionOpen the method

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• 11
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• 13

The paper at a glance, coloured by move. Click a square to open its question; empty squares are not decoded yet.

• 1Reciprocal Substitution FoldingReduction Formulae & TelescopingKey methodPureIntegration10 other sittings

  Same method, other sittings

  2009201220132014201620172018202020232025

  Worked solutionOpen the method

  AlsoReduction Formulae & Telescoping
• 2Induction with an InvariantKey methodPureSequences & Series2 other sittings

  Same method, other sittings

  20062018

  Worked solutionOpen the method
• 3Parametric & Polar AreasTunnelPureIntegration2 other sittings

  Same method, other sittings

  20112023

  Worked solutionOpen the method
• 5Infinite Descent & IrrationalityKey methodPureProof & Number Theory4 other sittings

  Same method, other sittings

  2011201320222023

  Worked solutionOpen the method
• 6Root Symmetry → CoefficientsKey methodPureComplex Numbers2 other sittings

  Same method, other sittings

  20212023

  Worked solutionOpen the method
• 7Induction with an InvariantKey methodPureProof & Number Theory2 other sittings

  Same method, other sittings

  20062018

  Worked solutionOpen the method
• 8Homogeneous ODE → $y=xu$Variable → Constant CoefficientsKey methodPureDifferential Equations4 other sittings

  Same method, other sittings

  2014201820202022

  Worked solutionOpen the method

  AlsoVariable → Constant Coefficients
• 9Spotting SHMKey methodMechanics4 other sittings

  Same method, other sittings

  2009201320162020

  Worked solutionOpen the method
• 13CDF of a Transformed VariableTunnelProb & StatsProbability & Statistics8 other sittings

  Same method, other sittings

  20092012201420172019202020212022

  Worked solutionOpen the method