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Question 6489: Missing Rational Addend and Substitution Defect

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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R0011-06489 · q-20261009-advance-20261013-r03-rational-number-0089

Original question and givens

Exact rational representations have nonzero denominators; a=1/2, b=-1/3. Negative input denominators are allowed. The target is -3/-6 and x+a+b=target. Give (x, x+a+b−target). Use exact reduced fractions with positive denominators, retaining /1 for integers.

  • G001 — Exact rational representations have nonzero denominators; a=1/2, b=-1/3. Negative input denominators are allowed. The target is -3/-6 and x+a+b=target. Give (x, x+a+b−target). Use exact reduced fractions with positive denominators, retaining /1 for integers.

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

raw a=[1, 2];raw b=[-1, 3]

After

a=1/2;b=-1/3

Conditions: none

Original denominators need only be nonzero;negative denominators are valid.Normalize to reduced positive-denominator fractions for exact arithmetic while retaining the original representations and sources.

Step identifiers and dependencies

Rule: nonzero_signed_rational_representation · Uses: G001

S002 · calculation

Before

target minus a := sub(1/2, 1/2)

After

target minus a = 0

Conditions: none

From x+a+b=target,subtract a first.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

missing rational addend := sub(0, -1/3)

After

missing rational addend = 1/3

Conditions: none

Then subtract b to obtain the unique rational addend x.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

reverse x+a := sum(1/3, 1/2)

After

reverse x+a = 5/6

Conditions: none

Substitute the recovered x back and add a.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

reverse x+a+b := sum(5/6, -1/3)

After

reverse x+a+b = 1/2

Conditions: none

Add the original b to reconstruct the original left side.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

missing addend substitution residual := sub(1/2, 1/2)

After

missing addend substitution residual = 0

Conditions: none

Subtract the original target from the substituted value;the result must be exactly0.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · implies

Before

x=1/3;target=1/2

After

substitution residual=0/1

Conditions: none

Audit the rearrangement by full substitution,not by copying the target or confusing zero residual with undefinedness.

Step identifiers and dependencies

Rule: rational_missing_addend_reverse_audit · Uses: G001, S006

Reverse checks

  • 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 missing addend substitution residual with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute reverse x+a+b with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute reverse x+a with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute missing rational addend with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute target minus a with exact rational arithmetic, not rounded decimals.
  • S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

(1/3, 0/1)

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: da331dc23490800b70c52f8a5f5791c1bc05ab10a7311ebd84ab184c78b39557
  • candidate record SHA-256: 9d7b1a32ab72acf55ebf59367fd99a360607e26683424fecf29022e83df4d561
  • semantic review receipt SHA-256: b9bbc1c947f477a9c4bb5a579368ac5265f2da4572ce612c30f3633ecaf4ae80
  • question-first witness SHA-256: 93f720df3ab3af13a792a3e6b443728e3c2a56276df839911f36569333236c55
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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