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SolveAsTheDerivativeOfAFunctionOverAPowerOfALogarithmOrAnInverse​(AngouriMath.​Entity,​AngouriMath.​Entity.​Variable)

 Method (no overloads)

Summary

The derivative of a quotient U/V^k for V a logarithm or an inverse
trigonometric function: (U/V^k)' = U'/V^k - k U V'/V^(k + 1), so the terms of the
integrand with V^(k + 1) below the bar are -k U V' over it, and
U = -B/(k V') for their sum B. Rubi's
x^3/((1 + a^2 x^2) atan(a x)^3) - 3 x^2/(2 a atan(a x)^2) is
(-x^3/(2 a atan(a x)^2))', and
1/((c + d x)(c - a + (d - b) x) ln(Q)) + ln(1 - Q)/((a + b x)(c + d x) ln(Q)^2), for
Q = (a + b x)/(c + d x), is (-ln(1 - Q)/((b c - a d) ln(Q)))'.

Remarks

Neither term is elementary on its own, so every split loses it, and by parts on either
leaves the other's question again; both were searches past the budget. The rational part
of B/(k V') is brought to lowest terms, where it is a constant or a polynomial for
these, and the answer is U/V^k only where its derivative is the whole integrand at
sampled points, the terms with lower powers of V included: where it is not, the
integrand is no such derivative, and this declines.
https://github.com/asc-community/AngouriMath/issues/233

























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