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Question 90: The Finite Expansion Includes Every k from Zero through n

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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← Question derivation index · Original question batch

P250-0090 · q-20261014-advance-20261109-r05-binomial-theorem-0040

Original question and givens

Use natural exponent n=14, including0, in a commutative coefficient setting. Give (n, coefficient_exponent_rows, boundary).

  • G001 — Use natural exponent n=14, including0, in a commutative coefficient setting. Give (n, coefficient_exponent_rows, boundary).

Definition and scope

n is a nonnegative integer and x,y commute. For n=0 use the polynomial empty-product identity.

Step-by-step derivation

S001 · implies

Before

n=14≥0; x,y commute

After

(x+y)^14 is a finite product of 14 factors

Conditions: none

Choose x or y from each factor; commutativity permits grouping products by the number of y choices.

Step identifiers and dependencies

Rule: finite_product · Uses: G001

S002 · implies

Before

choose exactly 0 of 14 factors to contribute y

After

C(14,0)=87178291200/(1·87178291200)=1

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 0 y positions and 14 x positions, giving coefficient 1.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S001

S003 · implies

Before

C(14,0)=1; choose y 0 times

After

1·x^14·y^0

Conditions: none

The x exponent is 14-0=14; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S002

S004 · implies

Before

choose exactly 1 of 14 factors to contribute y

After

C(14,1)=87178291200/(1·6227020800)=14

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 1 y positions and 13 x positions, giving coefficient 14.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S003

S005 · implies

Before

C(14,1)=14; choose y 1 times

After

14·x^13·y^1

Conditions: none

The x exponent is 14-1=13; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S004

S006 · implies

Before

choose exactly 2 of 14 factors to contribute y

After

C(14,2)=87178291200/(2·479001600)=91

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 2 y positions and 12 x positions, giving coefficient 91.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S005

S007 · implies

Before

C(14,2)=91; choose y 2 times

After

91·x^12·y^2

Conditions: none

The x exponent is 14-2=12; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S006

S008 · implies

Before

choose exactly 3 of 14 factors to contribute y

After

C(14,3)=87178291200/(6·39916800)=364

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 3 y positions and 11 x positions, giving coefficient 364.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S007

S009 · implies

Before

C(14,3)=364; choose y 3 times

After

364·x^11·y^3

Conditions: none

The x exponent is 14-3=11; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S008

S010 · implies

Before

choose exactly 4 of 14 factors to contribute y

After

C(14,4)=87178291200/(24·3628800)=1001

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 4 y positions and 10 x positions, giving coefficient 1001.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S009

S011 · implies

Before

C(14,4)=1001; choose y 4 times

After

1001·x^10·y^4

Conditions: none

The x exponent is 14-4=10; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S010

S012 · implies

Before

choose exactly 5 of 14 factors to contribute y

After

C(14,5)=87178291200/(120·362880)=2002

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 5 y positions and 9 x positions, giving coefficient 2002.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S011

S013 · implies

Before

C(14,5)=2002; choose y 5 times

After

2002·x^9·y^5

Conditions: none

The x exponent is 14-5=9; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S012

S014 · implies

Before

choose exactly 6 of 14 factors to contribute y

After

C(14,6)=87178291200/(720·40320)=3003

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 6 y positions and 8 x positions, giving coefficient 3003.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S013

S015 · implies

Before

C(14,6)=3003; choose y 6 times

After

3003·x^8·y^6

Conditions: none

The x exponent is 14-6=8; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S014

S016 · implies

Before

choose exactly 7 of 14 factors to contribute y

After

C(14,7)=87178291200/(5040·5040)=3432

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 7 y positions and 7 x positions, giving coefficient 3432.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S015

S017 · implies

Before

C(14,7)=3432; choose y 7 times

After

3432·x^7·y^7

Conditions: none

The x exponent is 14-7=7; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S016

S018 · implies

Before

choose exactly 8 of 14 factors to contribute y

After

C(14,8)=87178291200/(40320·720)=3003

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 8 y positions and 6 x positions, giving coefficient 3003.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S017

S019 · implies

Before

C(14,8)=3003; choose y 8 times

After

3003·x^6·y^8

Conditions: none

The x exponent is 14-8=6; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S018

S020 · implies

Before

choose exactly 9 of 14 factors to contribute y

After

C(14,9)=87178291200/(362880·120)=2002

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 9 y positions and 5 x positions, giving coefficient 2002.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S019

S021 · implies

Before

C(14,9)=2002; choose y 9 times

After

2002·x^5·y^9

Conditions: none

The x exponent is 14-9=5; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S020

S022 · implies

Before

choose exactly 10 of 14 factors to contribute y

After

C(14,10)=87178291200/(3628800·24)=1001

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 10 y positions and 4 x positions, giving coefficient 1001.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S021

S023 · implies

Before

C(14,10)=1001; choose y 10 times

After

1001·x^4·y^10

Conditions: none

The x exponent is 14-10=4; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S022

S024 · implies

Before

choose exactly 11 of 14 factors to contribute y

After

C(14,11)=87178291200/(39916800·6)=364

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 11 y positions and 3 x positions, giving coefficient 364.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S023

S025 · implies

Before

C(14,11)=364; choose y 11 times

After

364·x^3·y^11

Conditions: none

The x exponent is 14-11=3; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S024

S026 · implies

Before

choose exactly 12 of 14 factors to contribute y

After

C(14,12)=87178291200/(479001600·2)=91

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 12 y positions and 2 x positions, giving coefficient 91.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S025

S027 · implies

Before

C(14,12)=91; choose y 12 times

After

91·x^2·y^12

Conditions: none

The x exponent is 14-12=2; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S026

S028 · implies

Before

choose exactly 13 of 14 factors to contribute y

After

C(14,13)=87178291200/(6227020800·1)=14

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 13 y positions and 1 x positions, giving coefficient 14.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S027

S029 · implies

Before

C(14,13)=14; choose y 13 times

After

14·x^1·y^13

Conditions: none

The x exponent is 14-13=1; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S028

S030 · implies

Before

choose exactly 14 of 14 factors to contribute y

After

C(14,14)=87178291200/(87178291200·1)=1

Conditions: none

Count orderings of 14 positions and divide by reorderings within the 14 y positions and 0 x positions, giving coefficient 1.

Step identifiers and dependencies

Rule: subset_count · Uses: G001, S029

S031 · implies

Before

C(14,14)=1; choose y 14 times

After

1·x^0·y^14

Conditions: none

The x exponent is 14-14=0; the two exponents still sum to 14.

Step identifiers and dependencies

Rule: group_like_terms · Uses: G001, S030

S032 · implies

Before

all k=0 through 14 have been accounted for

After

(x+y)^14=1·x^14·y^0 + 14·x^13·y^1 + 91·x^12·y^2 + 364·x^11·y^3 + 1001·x^10·y^4 + 2002·x^9·y^5 + 3003·x^8·y^6 + 3432·x^7·y^7 + 3003·x^6·y^8 + 2002·x^5·y^9 + 1001·x^4·y^10 + 364·x^3·y^11 + 91·x^2·y^12 + 14·x^1·y^13 + 1·x^0·y^14

Conditions: none

Every x/y choice belongs to exactly one k class, so this is the complete finite expansion, not just endpoint terms.

Step identifiers and dependencies

Rule: collect_all_terms · Uses: G001, S031

Reverse checks

  • S032 · premise_and_result_audit — There are n+1 coefficient positions, with the complete range of k retained.
  • S031 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S030 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S029 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S028 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S027 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S026 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S025 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S024 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S023 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S022 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S021 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S020 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S019 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S018 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S017 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S016 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S015 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S014 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S013 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S012 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S011 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S010 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S009 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S008 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S007 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S006 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S005 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S004 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S003 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
  • S002 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
  • S001 · premise_and_result_audit — This is not an infinite expansion for a noninteger power or a claim for noncommuting multiplication.

Result

(14, [[0, 1, 14, 0], [1, 14, 13, 1], [2, 91, 12, 2], [3, 364, 11, 3], [4, 1001, 10, 4], [5, 2002, 9, 5], [6, 3003, 8, 6], [7, 3432, 7, 7], [8, 3003, 6, 8], [9, 2002, 5, 9], [10, 1001, 4, 10], [11, 364, 3, 11], [12, 91, 2, 12], [13, 14, 1, 13], [14, 1, 0, 14]], complete_k_zero_through_n_coefficients)

The full expansion consists of all displayed monomials, in the same order as the answer rows.

This question review and source binding

Review date: 2026-10-24

Original questions, answers, step expressions, numeric ASTs and historical records are retained. Source candidate labels remain historical and are not overwritten as formal proof.

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