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Question 28612: Average Rate of a Real Affine Function

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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R0056-28612 · q-20261005-advance-20261006-r03-rate-of-change-0062

Original question and givens

On the full real domain, f(x)=(-1)x+(26). For distinct inputs 0 and -12, find the average rate of change. Give a reduced fraction with positive denominator, retaining /1 for integers.

  • G001 — On the full real domain, f(x)=(-1)x+(26). For distinct inputs 0 and -12, find the average rate of change. Give a reduced fraction with positive denominator, 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

source roles = [qf-rate-affine-average, affine_average]

After

derived = [exact_average_rate_fraction]

Conditions: none

Use the declared scalar/set/Yes-No/fraction answer role;integer fractions retain/1.Do not add an undeclared domain or change original bilingual data,formulas or questions.

Step identifiers and dependencies

Rule: R56_source_answer_role_and_EXACT_family_interface · Uses: G001

S002 · calculation

Before

Rate ORIGINAL x1 minus x0 := sub(-12, 0)

After

Rate ORIGINAL x1 minus x0 = -12

Conditions: none

Perform exact rational arithmetic on the ORIGINAL roles.SAFE bounds raw inputs only;derived integers are unbounded and never approximated by floats.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

Rate affine ORIGINAL m times x0 := mul(-1, 0)

After

Rate affine ORIGINAL m times x0 = 0

Conditions: none

Perform exact rational arithmetic on the ORIGINAL roles.SAFE bounds raw inputs only;derived integers are unbounded and never approximated by floats.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

Rate affine ORIGINAL endpoint0 plus b := sum(0, 26)

After

Rate affine ORIGINAL endpoint0 plus b = 26

Conditions: none

Perform exact rational arithmetic on the ORIGINAL roles.SAFE bounds raw inputs only;derived integers are unbounded and never approximated by floats.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

Rate affine ORIGINAL m times x1 := mul(-1, -12)

After

Rate affine ORIGINAL m times x1 = 12

Conditions: none

Perform exact rational arithmetic on the ORIGINAL roles.SAFE bounds raw inputs only;derived integers are unbounded and never approximated by floats.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

Rate affine ORIGINAL endpoint1 plus b := sum(12, 26)

After

Rate affine ORIGINAL endpoint1 plus b = 38

Conditions: none

Perform exact rational arithmetic on the ORIGINAL roles.SAFE bounds raw inputs only;derived integers are unbounded and never approximated by floats.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · implies

Before

source roles = [-1, 26, 0, -12]

After

derived = [[26, 38], -1]

Conditions: none

Substitute both endpoints in the WHOLE law f(x)=mx+b.The intercept cancels,so dy=m*dx;m=0 is allowed.This is an endpoint secant computation,not a substituted derivative.

Step identifiers and dependencies

Rule: Rate_WHOLE_affine_endpoint_subtraction · Uses: G001, S006

S008 · calculation

Before

Rate ORIGINAL y1 minus y0 := sub(38, 26)

After

Rate ORIGINAL y1 minus y0 = 12

Conditions: none

Perform exact rational arithmetic on the ORIGINAL roles.SAFE bounds raw inputs only;derived integers are unbounded and never approximated by floats.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · calculation

Before

Rate ORIGINAL dy over dx := div(12, -12)

After

Rate ORIGINAL dy over dx = -1

Conditions: none

Perform exact rational arithmetic on the ORIGINAL roles.SAFE bounds raw inputs only;derived integers are unbounded and never approximated by floats.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · implies

Before

source roles = [0, -12, 26, 38, -12, 12]

After

derived = [-1/1]

Conditions: none

Keep the SAME endpoint orientation:(y1-y0)/(x1-x0).Both differences may reverse together,not just one.The result may be negative or0;normalize a positive denominator and retain/1.This finite endpoint rate is not a general derivative certificate.

Step identifiers and dependencies

Rule: Rate_oriented_quotient_reverse_BOTH_differences · Uses: G001, S009

Reverse checks

  • S010 · premise_and_result_audit — Reverse-check EACH original datum and premise,retaining indices,signs and strict/non-strict boundaries.A correct final answer cannot replace the derivation obligations.This is candidate teaching/exact checking,not formal proof or publication clearance.
  • S009 · premise_and_result_audit — Recompute Rate ORIGINAL dy over dx with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Recompute Rate ORIGINAL y1 minus y0 with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Reverse-check EACH original datum and premise,retaining indices,signs and strict/non-strict boundaries.A correct final answer cannot replace the derivation obligations.This is candidate teaching/exact checking,not formal proof or publication clearance.
  • S006 · premise_and_result_audit — Recompute Rate affine ORIGINAL endpoint1 plus b with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute Rate affine ORIGINAL m times x1 with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute Rate affine ORIGINAL endpoint0 plus b with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute Rate affine ORIGINAL m times x0 with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute Rate ORIGINAL x1 minus x0 with exact rational arithmetic, not rounded decimals.
  • S001 · premise_and_result_audit — Reverse-check EACH original datum and premise,retaining indices,signs and strict/non-strict boundaries.A correct final answer cannot replace the derivation obligations.This is candidate teaching/exact checking,not formal proof or publication clearance.

Result

-1/1

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: 4b38181913aeb465d85e1acf05c90b9fc1c68c7f52746fc2c2c4ced8eb074fbc
  • candidate record SHA-256: c892539cf74c48fe34e838f7b76be523c27bb776b2f512d10857485b76783ebd
  • semantic review receipt SHA-256: 8bbda4edbed7078634ae88342998c79bcfb95de96187fac119c3b08e0adb0bc8
  • question-first witness SHA-256: 3edafa72d63d16a22414892b55806430e0a25b15b926d04f312550179607759f
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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