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AsTheDerivativeOfALowerPowerOfALinearBesideAFunction​(System.​Collections.​Generic.​IReadOnlyList{AngouriMath.​Entity},​AngouriMath.​Entity.​Variable)

 Method (no overloads)

Summary

A sum whose terms are not elementary apart, integrated by parts the other way in some of the terms that are a
power L^(-k), k >= 2, of one linear L beside a function F with x only inside transcendental functions -- the power integrated, Q = L^(1 - k)/((1 - k) L'), and F differentiated -- where what that leaves, -Q F', cancels against the other terms: then the sum is
(Q F)' summed over those terms. psi_1(a + b x)/x^2 - b psi_2(a + b x)/x is
(-psi_1(a + b x)/x)', Rubi's 8.6, and neither of its terms is elementary.
https://github.com/asc-community/AngouriMath/issues/2075

Remarks

Some, not all: in psi_1(x)/(2 + 3 x)^3 - psi_2(x)/(6 (2 + 3 x)^2) the second term has a power of -2 as well,
and is what the first leaves. So each set of them is tried, the smallest first, and rejected at a point by adding
numbers before anything is simplified. Nothing is asked, so a remainder that does not cancel declines rather than
becoming a question: lowering the power toward L^(-1) raises the order of F, and a remainder in
F' is no nearer an answer.

























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