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R0016-08524 · q-20261007-advance-20261008-r04-derivative-0024
On all R, f(t)=(11)t+(-20). Find f′(1) in this affine model.
G001 — On all R, f(t)=(11)t+(-20). Find f′(1) in this affine model.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.
Before
declared real formula on all R;derivative means the two-sided h->0 quotient limit
After
finite-step evaluation and derivative existence are separate
Conditions: none
A derivative is the two-sided limit of[f(x+h)−f(x)]/h as h→0 with h≠0.One finite evaluation is not evidence that an arbitrary function is differentiable.
Rule: derivative_limit_definition_scope · Uses: G001
Before
affine m*x := mul(11, 1)
After
affine m*x = 11
Conditions: none
Evaluate exactly with this step's source operands and operation order.Check a denominator is nonzero before division.
Rule: exact_rational_arithmetic · Uses: G001, S001
Before
affine f(x) := sum(11, -20)
After
affine f(x) = -9
Conditions: none
Evaluate exactly with this step's source operands and operation order.Check a denominator is nonzero before division.
Rule: exact_rational_arithmetic · Uses: G001, S002
Before
f(t)=(11)*t+(-20);x=1;f(x)=-9;h!=0
After
f(x+h)-f(x)=(11)*h;quotient=11
Conditions: none
Expand m(x+h)+b−(mx+b);the intercept and mx cancel,leaving mh.Cancel h only for h≠0,including the valid m=0 case.
Rule: affine_increment_cancellation · Uses: G001, S003
Before
for every h!=0 the quotient is 11
After
two-sided derivative at 1=11
Conditions: none
The quotient is identically m throughout a punctured neighborhood,so its two-sided limit is m.The point value or intercept is not the derivative.
Rule: constant_quotient_limit · Uses: G001, S004
S005 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.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 affine f(x) with exact rational arithmetic, not rounded decimals.S002 · premise_and_result_audit — Recompute affine m*x 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.11
The full substitutions and premise checks give the original answer; source identity,format and status are unchanged.
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.
input commit: 0f7be61e2c22317a4075561dc822c87d881a50dboriginal question SHA-256: 979f2a1eb9f660d530c9c596cfaae8fdbe4596ddd6d75ebde58ff82da846c2b7candidate record SHA-256: 8f3c68fccd701bd46b9cfaf8e281ba5f4c561562f952a0596a26ce742b4895e5semantic review receipt SHA-256: 00fcddb10a9fb0f56697308976a52e68e2537472bd8e68ecbe96d3c4553f4ad2question-first witness SHA-256: 198e04380b2d32aef2375b07ca0df1f8afa454d1184993173fad8a3c9187a3d1Lean: NOT_RUN · human review: NOT_PERFORMED