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Question 10080: Specified Coefficient of a Factor Product

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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R0019-10080 · q-20261003-r03-factorization-0055

Original question and givens

In Q[x], coefficient vectors are ordered from lowest to highest power. Find the coefficient of x^4 in the product of [-1, 1] and [6, -1].

  • G001 — In Q[x], coefficient vectors are ordered from lowest to highest power. Find the coefficient of x^4 in the product of [-1, 1] and [6, -1].

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

Q[x];ascending coefficients;input vectors may have trailing zeros

After

equality uses every normalized coefficient,not numerical sampling

Conditions: none

Preserve the original factor order and vectors.Normalization removes only trailing high-power zeros;do not reorder source factors by semantic identity or infer polynomial equality from one point.

Step identifiers and dependencies

Rule: factorization_coefficient_identity_scope · Uses: G001

S002 · implies

Before

raw left=[-1, 1];raw right=[6, -1]

After

normalized left=[-1, 1];normalized right=[6, -1]

Conditions: none

Remove trailing zeros only,not internal zeros or the original vector order.Empty and all-zero vectors both represent zero.

Step identifiers and dependencies

Rule: factor_vectors_trailing_zero_normalization · Uses: G001, S001

S003 · implies

Before

power k=4;left=[-1, 1];right=[6, -1]

After

all index pairs i+j=k=[]

Conditions: none

Ascending-vector indices are powers.Collect every valid pair with i+j=k;polynomial multiplication is not entrywise multiplication.

Step identifiers and dependencies

Rule: product_coefficient_complete_index_pairs · Uses: G001, S002

S004 · implies

Before

power k=4;no valid contributing index pairs

After

coefficient=0

Conditions: none

With no contributing pair the empty sum is0.Do not use negative indexing or invent a higher coefficient.

Step identifiers and dependencies

Rule: empty_coefficient_sum_zero · 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 — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • 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

0

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: b22ca0616de7ec6ccb80fc521794ca101764f9c4e2f558278cae926e61d35bce
  • candidate record SHA-256: ebd7e9e9f337cfa79f13ed54492683d50deeedd54179b74f6b51782f51aa820a
  • semantic review receipt SHA-256: eeb35dc5daab92234bf72827627392b47f38ead4cfb574d4373bebc43c09fbf5
  • question-first witness SHA-256: 3cf8e0d3a00b0df1994db2bfde81f4a31b382e170bdda83ea3d0b68da64e8419
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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