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Take a root of a perfect square with a leading coefficient of no known sign - #1884

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a-power-of-a-perfect-square-is-integrated-as-one
Oct 14, 2026
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Rafael-SOWNet merged 3 commits into
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a-power-of-a-perfect-square-is-integrated-as-one

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Part of #718

SolveByTakingARootOfAPerfectSquare took (a (w + h)^2)^r as a^r |w + h|^(2r) only for a leading coefficient whose sign it could establish, so sqrt(c d^2 + 2 c d e x + c e^2 x^2) was declined. The identity holds for every nonzero a as long as w + h is real: (w + h)^2 is positive, so Log(a (w + h)^2) is Log(a) + 2 ln|w + h|. A negative number was already read that way, and a symbol of unknown sign now is too.

SolveByWritingAPowerOfASquareAsAPowerOfItsRoot also takes a linear factor of the integrand that is a multiple of the square's root as the root itself. For (d + e x)^(-1 - 2p) (c d^2 + 2 c d e x + c e^2 x^2)^p, that gathers the two powers into (d + e x)^(-1), where before it had two powers of two linears.

Measured

intbench, this branch against master 790feec, 5 s budget. The pocket was 1.2.1.2, 1.2.1.3, 1.2.1.4, 1.2.1.6, 1.2.1.9, 1.2.2.2, 1.3.2, 5.3.5 and 7.1.5 in full (7,422 rows), plus the usual family sample:

master this branch
pocket 7,262 solved 7,274 solved
families 0–8 sample identical except one more solved in family 3
wrong / error 0 / 0 0 / 0

The moves, re-run alone: 13 rows went from unsolved to solved, and none went the other way.

  • 1.2.1.2:1199, 1209, 1220, 1235, 1244, 1254, 1280, 1281 and 2718
  • 6.5.3:115 sqrt(a + a sech(c + d x))
  • 7.1.5:485 and 486, asinh(sqrt(b x^2 - 1)) beside its root, where the inverse's derivative holds sqrt(b x^2)

Every new answer was checked exactly with exactcheck (exact pins, 50 and 2,000 digits, four points, three pin sets with the leading coefficient negative in two): 276 of 276 diff 0. The gate passes. The suite passes in two halves, 1,856 and 13,522, which is master's 15,373 plus the 5 new tests. Run whole, the test host hits the 8 GB memory guard here as on master (#1883).

1/sqrt(c d^2 + 2 c d e x + c e^2 x^2) was answered by 2.5.0 in 411 characters and declined on master. It is 61 characters now.

Still declined in the same file, and left for another PR: 1.2.1.2:2389–2393, (d + e x)^(-3 - 2p) ((d + e x)(a e + c d x))^p, which wants t = (a e + c d x)/(d + e x).

🤖 Generated with Claude Code

https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura

Rafael-SOWNet and others added 3 commits October 14, 2026 09:25
…n sign

(a (w + h)^2)^r is a^r |w + h|^(2r) for every nonzero a where w + h is
real, since its square is positive: a negative number was read so
already, and a symbol of no known sign is now. And a linear of the
integrand that is a multiple of the square's root is taken as the root,
so that its power and the square's gather into one.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura
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 14, 2026
@Rafael-SOWNet
Rafael-SOWNet merged commit acd4702 into master Oct 14, 2026
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@github-project-automation github-project-automation Bot moved this from Todo to Done in AngouriMath Oct 14, 2026
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