Explore related knowledge and questions →

Question 28069: Positive Square-Root Iterates Use Exact Rational Newton Steps

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

Return to catalogue page 141

← Question derivation index · Original question batch

R0055-28069 · q-20261015-pulse-20261119-r01-0069

Original question and givens

Use positive radicand A=20, positive initial iterate=5, and attempted-step budget=1; f(x)=x^2−A. Give (radicand, initial_iterate, step_budget, step_records, status, final_iterate, final_absolute_residual, general_Newton_proof_claim, finite_scope).

  • G001 — Use positive radicand A=20, positive initial iterate=5, and attempted-step budget=1; f(x)=x^2−A. Give (radicand, initial_iterate, step_budget, step_records, status, final_iterate, final_absolute_residual, general_Newton_proof_claim, finite_scope).

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

source roles = [qf-mod50-newton-square-root-orbit, newton-square-root-orbit]

After

derived = [[radicand, initial_iterate, step_budget, step_records, status, final_iterate, final_absolute_residual, general_Newton_proof_claim, finite_scope]]

Conditions: none

List this scalar/label/set/point answer role or mode-specific ordered fields,not an imposed universal tuple.Retain legacy domain/underscore operation and integer fractions with/1;original bilingual snapshots stay unchanged.

Step identifiers and dependencies

Rule: source_answer_roles_or_ordered_fields_without_JS · Uses: G001

S002 · calculation

Before

Newton sqrt attempt0 ORIGINAL square := mul(5, 5)

After

Newton sqrt attempt0 ORIGINAL square = 25

Conditions: none

Substitute original roles exactly,without floating approximation or changed operands;extra teaching identities add no source-domain restrictions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

Newton sqrt attempt0 ORIGINAL signed residual := sub(25, 20)

After

Newton sqrt attempt0 ORIGINAL signed residual = 5

Conditions: none

Substitute original roles exactly,without floating approximation or changed operands;extra teaching identities add no source-domain restrictions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

Newton sqrt attempt0 ORIGINAL A over x := div(20, 5)

After

Newton sqrt attempt0 ORIGINAL A over x = 4

Conditions: none

Substitute original roles exactly,without floating approximation or changed operands;extra teaching identities add no source-domain restrictions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

Newton sqrt attempt0 ORIGINAL x plus A over x := sum(5, 4)

After

Newton sqrt attempt0 ORIGINAL x plus A over x = 9

Conditions: none

Substitute original roles exactly,without floating approximation or changed operands;extra teaching identities add no source-domain restrictions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

Newton sqrt attempt0 ORIGINAL half update := div(9, 2)

After

Newton sqrt attempt0 ORIGINAL half update = 9/2

Conditions: none

Substitute original roles exactly,without floating approximation or changed operands;extra teaching identities add no source-domain restrictions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

Newton sqrt ORIGINAL final square EVEN steps0 := mul(9/2, 9/2)

After

Newton sqrt ORIGINAL final square EVEN steps0 = 81/4

Conditions: none

Substitute original roles exactly,without floating approximation or changed operands;extra teaching identities add no source-domain restrictions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · calculation

Before

Newton sqrt ORIGINAL final signed residual := sub(81/4, 20)

After

Newton sqrt ORIGINAL final signed residual = 1/4

Conditions: none

Substitute original roles exactly,without floating approximation or changed operands;extra teaching identities add no source-domain restrictions.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · implies

Before

source roles = [20, 5, 1]

After

derived = [[[0, 5, 5, updated, 9/2]], step_budget_exhausted, 9/2, 1/4, No]

Conditions: none

Positive A/x0 keep(x+A/x)/2 positive and division defined;an exact root stops first.Always compute the final absolute residual,even at steps0.It is|x²-A|,not an unprovided forward error|x-sqrt(A)|,and a finite orbit is not a general convergence certificate.

Step identifiers and dependencies

Rule: Newton_sqrt_positive_iteration_ROOT_FIRST_residual_NOT_forward_error · Uses: G001, S008

Reverse checks

  • S009 · premise_and_result_audit — Reverse-check complete original data,operands and premises;finite checks,conditional reasoning,formal proof and publication authority remain distinct.
  • S008 · premise_and_result_audit — Recompute Newton sqrt ORIGINAL final signed residual with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Recompute Newton sqrt ORIGINAL final square EVEN steps0 with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute Newton sqrt attempt0 ORIGINAL half update with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute Newton sqrt attempt0 ORIGINAL x plus A over x with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute Newton sqrt attempt0 ORIGINAL A over x with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute Newton sqrt attempt0 ORIGINAL signed residual with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute Newton sqrt attempt0 ORIGINAL square with exact rational arithmetic, not rounded decimals.
  • S001 · premise_and_result_audit — Reverse-check complete original data,operands and premises;finite checks,conditional reasoning,formal proof and publication authority remain distinct.

Result

(20, 5, 1, [[0, 5, 5, updated, 9/2]], step_budget_exhausted, 9/2, 1/4, No, finite_square_root_orbit_does_not_prove_a_general_Newton_theorem)

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: 5dc376e062c37d1304f15ec3b229743e0865cf6dc57e796579961ffeecf64327
  • candidate record SHA-256: 5ffaaa72208f20822070a80a3990063a38d26a12d1eb2cd1570633ee8f1b5ed2
  • semantic review receipt SHA-256: 6af367dae24a584f3596525c4953bbc2115343efd68cc9083693eb5c1ef2e683
  • question-first witness SHA-256: 611eb69f3716404b968296a8b0d7d8c61b5ca18129d406f1ff9c7c11e10ffb4e
  • Lean: NOT_RUN · human review: NOT_PERFORMED
Same-source full JSON