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Write a symbolic cubic with a repeated root over its roots - #1933

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Rafael-SOWNet merged 3 commits into
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a-cubic-with-a-repeated-root-is-split-over-it
Oct 17, 2026
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Rafael-SOWNet merged 3 commits into
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a-cubic-with-a-repeated-root-is-split-over-it

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A cubic below the bar with symbolic coefficients and a discriminant that vanishes identically is a (x - r)^2 (x - t), with the double root r = (9ad - bc)/(2(b² - 3ac)) and the simple root t = (4abc - 9a²d - b³)/(a(b² - 3ac)) (a triple root a (x + b/3a)^3 where b² - 3ac vanishes too). It is written so before the partial fractions; each candidate is checked by expanding it back against the cubic. 1/(x^3 - 3b x + 2b^(3/2)) was left unevaluated and is answered in 84 ms.

Part of #718 — Rubi's 1.3.1:8.

Measured against master b2ef509, both arms in one chain:

  • the pocket (the 626 rows of the cubic's shape across all families): 621 → 622 solved, 0 wrong either side;
  • family 1 at 40 a file, family 0 whole, families 2–8 sampled: one move, 1.3.1:8 unsolved → solved, confirmed alone;
  • the benchmark gate passed; the suite passed (15,552). After merging master 5bf5b1b: built for every target, suite 15,555 passed.

Recorded in BREAKING-CHANGES.md.

🤖 Generated with Claude Code

https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura

Rafael-SOWNet and others added 3 commits October 17, 2026 20:15
A cubic below the bar whose discriminant vanishes identically is
a (x - r)^2 (x - s), with r and s rational in its coefficients, or a cube
where b^2 - 3ac vanishes too. 1/(9x^3 - 9bx + 2 sqrt(3) b^(3/2)) was left
unevaluated (Rubi's 1.3.1:8) and so written is answered in half a second.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura
…ated-root-is-split-over-it

# Conflicts:
#	Sources/AngouriMath/Functions/Continuous/Integration/IndefiniteIntegralSolver.cs
#	Sources/AngouriMath/Functions/Continuous/Integration/Integration.Definition.cs
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura
@Rafael-SOWNet Rafael-SOWNet added this to the 2.6.0 milestone Oct 17, 2026
@Rafael-SOWNet
Rafael-SOWNet merged commit c1647fd into master Oct 17, 2026
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@github-project-automation github-project-automation Bot moved this from Todo to Done in AngouriMath Oct 17, 2026
@Rafael-SOWNet
Rafael-SOWNet deleted the a-cubic-with-a-repeated-root-is-split-over-it branch October 29, 2026 00:43
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