Primitive of Square of Hyperbolic Cotangent Function

Theorem

$\ds \int \coth^2 x \rd x = x - \coth x + C$

where $C$ is an arbitrary constant.


Proof

\(\ds \int \coth^2 x \rd x\) \(=\) \(\ds \int \paren {1 + \csch^2 x} \rd x\) Difference of Squares of Hyperbolic Cotangent and Cosecant
\(\ds \) \(=\) \(\ds \int 1 \rd x + \int \csch^2 x \rd x\) Linear Combination of Primitives
\(\ds \) \(=\) \(\ds \int 1 \rd x - \coth x + C\) Primitive of Square of Hyperbolic Cosecant Function
\(\ds \) \(=\) \(\ds x - \coth x + C\) Primitive of Constant

$\blacksquare$


Sources

  • 1968: Murray R. Spiegel: Mathematical Handbook of Formulas and Tables ... (previous) ... (next): $\S 14$: General Rules of Integration: $14.34$
  • 2009: Murray R. Spiegel, Seymour Lipschutz and John Liu: Mathematical Handbook of Formulas and Tables (3rd ed.) ... (previous) ... (next): $\S 16$: Indefinite Integrals: General Rules of Integration: $16.34.$