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Question 2245: An Initial Value Check Is Not an ODE Check

On this page
  1. Original question and givens
  2. Definition and scope
  3. Step-by-step derivation
  4. Reverse checks
  5. Result
  6. This question review and source binding

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R0003-02245 · q-20261013-advance-20261021-r04-initial-value-problem-0020

Original question and givens

Use the integer polynomial candidate with ascending-power coefficients=[9, 2, 1]. Initial data and ODE residuals are separate obligations. Neither a finite grid nor an initial-value match proves existence, uniqueness, a general solution or an identity on an entire interval. x0=2, required y0=17. Give (coefficients,x0,y(x0),required y0,match?).

  • G001 — Use the integer polynomial candidate with ascending-power coefficients=[9, 2, 1]. Initial data and ODE residuals are separate obligations. Neither a finite grid nor an initial-value match proves existence, uniqueness, a general solution or an identity on an entire interval. x0=2, required y0=17. Give (coefficients,x0,y(x0),required y0,match?).

Definition and scope

Use the original question domain, assumptions and cited MKO definitions. This item has second-context mathematical and bilingual review, with the model, answer and every arithmetic step independently recomputed from the original parameters; the source question remains a candidate.

Step-by-step derivation

S001 · implies

Before

candidate polynomial ascending coefficients=[9, 2, 1]

After

initial point=2; required y₀=17

Conditions: none

Retain the polynomial and initial data;the residual grid need not contain the initial point,so evaluate it separately.

Step identifiers and dependencies

Rule: candidate_IVP_data · Uses: G001

S002 · implies

Before

initial y ascending coefficients=[9, 2, 1]

After

evaluate at x=2

Conditions: none

Evaluate ascending coefficients by Horner from the highest nonzero term down;ignoring redundant top zero terms changes neither the function nor the retained original list.

Step identifiers and dependencies

Rule: polynomial_evaluation_order · Uses: G001, S001

S003 · calculation

Before

initial y Horner multiply before degree1 := mul(1, 2)

After

initial y Horner multiply before degree1 = 2

Conditions: none

Multiply by the same evaluation point first.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

initial y Horner add degree1 := sum(2, 2)

After

initial y Horner add degree1 = 4

Conditions: none

Then add the full coefficient at this position.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

initial y Horner multiply before degree0 := mul(4, 2)

After

initial y Horner multiply before degree0 = 8

Conditions: none

Multiply by the same evaluation point first.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

initial y Horner add degree0 := sum(8, 9)

After

initial y Horner add degree0 = 17

Conditions: none

Then add the full coefficient at this position.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · implies

Before

y(2)=17; required=17

After

value condition=Yes

Conditions: none

Compare the actual function value at the initial point,not another grid point.

Step identifiers and dependencies

Rule: initial_value_condition · Uses: G001, S006

S008 · implies

Before

initial data agree or disagree

After

no differential-equation assertion from initial data alone

Conditions: none

Matching initial data do not by themselves check the differential equation or prove an existence-uniqueness theorem.

Step identifiers and dependencies

Rule: initial_only_scope · Uses: G001, S007

Reverse checks

  • S008 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S007 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S006 · premise_and_result_audit — Recompute initial y Horner add degree0 with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute initial y Horner multiply before degree0 with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute initial y Horner add degree1 with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute initial y Horner multiply before degree1 with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

([9, 2, 1], 2, 17, 17, Yes)

The full substitutions and premise checks give the original answer; source identity,format and status are unchanged.

This question review and source binding

Review date: 2026-10-26

Original questions, answers, step expressions, numeric ASTs and historical records are retained. Source candidate labels remain historical and are not overwritten as formal proof.

Source hashes and review receipts
  • input commit: 0f7be61e2c22317a4075561dc822c87d881a50db
  • original question SHA-256: 43dc2380c6aed896fee36323f3e66dd21509af1f299d200810f0cab34b4b41b1
  • candidate record SHA-256: ec74379920768de9b3c8b81eedd2b92e913bfe599cb98580f76db949c903bb79
  • semantic review receipt SHA-256: 5dbc70ebd5f74b23384c93b63a2b1d6519e206c79f22ae16a6c2d7483cea783f
  • question-first witness SHA-256: cf121c8dd2fec13aa118b04b049ee39494f1d6d9ecdc13514cafb78c0fc021fa
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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