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Question 6416: Rational Division Eligibility and Multiplication Back

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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R0011-06416 · q-20261009-advance-20261013-r03-rational-number-0066

Original question and givens

Exact rational representations have nonzero denominators; a=16/-3, b=17/-4. Negative input denominators are allowed. Give (is b nonzero?, a/b or undefined, (a/b)b or undefined). Use exact reduced fractions with positive denominators, retaining /1 for integers.

  • G001 — Exact rational representations have nonzero denominators; a=16/-3, b=17/-4. Negative input denominators are allowed. Give (is b nonzero?, a/b or undefined, (a/b)b or undefined). 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=[16, -3];raw b=[17, -4]

After

a=-16/3;b=-17/4

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

guarded rational quotient := div(-16/3, -17/4)

After

guarded rational quotient = 64/51

Conditions: none

Use the exact quotient only after checking b≠0.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

rational reverse multiplication := mul(64/51, -17/4)

After

rational reverse multiplication = -16/3

Conditions: none

Multiply back by the same divisor to recover a.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · implies

Before

b=-17/4≠0;quotient=64/51

After

quotient·b=-16/3=a

Conditions: none

This division/reverse-multiplication chain requires a nonzero divisor;it is not a formal proof of the entire rational-number structure.

Step identifiers and dependencies

Rule: rational_nonzero_division_reversal · Uses: G001, S003

Reverse checks

  • S004 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S003 · premise_and_result_audit — Recompute rational reverse multiplication with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute guarded rational quotient 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

(Yes, 64/51, -16/3)

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: 1bd97b4550a176b275f2d5b19cd0db205571e18e8c43748ac4afafd707cdcca4
  • candidate record SHA-256: 5606473761dea3388ae164a961f8eced51684bcb21b8a7b071017c26db0e1785
  • semantic review receipt SHA-256: b9bbc1c947f477a9c4bb5a579368ac5265f2da4572ce612c30f3633ecaf4ae80
  • question-first witness SHA-256: 93f720df3ab3af13a792a3e6b443728e3c2a56276df839911f36569333236c55
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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