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Question 28056: Positive Square-Root Iterates Use Exact Rational Newton Steps On this page Original question and givens Definition and scope Step-by-step derivation Reverse checks Result This question review and source binding Return to catalogue page 141
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This teaching derivation has second-context AI mathematical and bilingual semantic review, limited to the model and assumptions stated in this question. It has no human review or new Lean proof and does not promote the original question or MKO to Canonical truth.
R0055-28056 · q-20261015-pulse-20261119-r01-0056
Original question and givens Use positive radicand A=7, positive initial iterate=2, 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=7, positive initial iterate=2, 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(2, 2) After
Newton sqrt attempt0 ORIGINAL square = 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, S001
S003 · calculation Before
Newton sqrt attempt0 ORIGINAL signed residual := sub(4, 7) After
Newton sqrt attempt0 ORIGINAL signed residual = -3 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(7, 2) After
Newton sqrt attempt0 ORIGINAL A over x = 7/2 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, S003
S005 · calculation Before
Newton sqrt attempt0 ORIGINAL x plus A over x := sum(2, 7/2) After
Newton sqrt attempt0 ORIGINAL x plus A over x = 11/2 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, S004
S006 · calculation Before
Newton sqrt attempt0 ORIGINAL half update := div(11/2, 2) After
Newton sqrt attempt0 ORIGINAL half update = 11/4 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, S005
S007 · calculation Before
Newton sqrt ORIGINAL final square EVEN steps0 := mul(11/4, 11/4) After
Newton sqrt ORIGINAL final square EVEN steps0 = 121/16 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(121/16, 7) After
Newton sqrt ORIGINAL final signed residual = 9/16 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 = [7, 2, 1] After
derived = [[[0, 2, -3, updated, 11/4]], step_budget_exhausted, 11/4, 9/16, 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 (7, 2, 1, [[0, 2, -3, updated, 11/4]], step_budget_exhausted, 11/4, 9/16, 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: 0f7be61e2c22317a4075561dc822c87d881a50dboriginal question SHA-256: 8681d4fb23c49641f30cd041a20df1742093befc57f45730c8ee8b9a5accb475candidate record SHA-256: 835d368412211ee14e6a0f97a5f358923d48ce04f406ff29ada31167437706c9semantic review receipt SHA-256: 6af367dae24a584f3596525c4953bbc2115343efd68cc9083693eb5c1ef2e683question-first witness SHA-256: 611eb69f3716404b968296a8b0d7d8c61b5ca18129d406f1ff9c7c11e10ffb4eLean: NOT_RUN · human review: NOT_PERFORMEDSame-source full JSON