Primitive of Hyperbolic Tangent of a x
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Theorem
- $\ds \int \tanh a x \rd x = \frac {\map \ln {\cosh a x} } a + C$
Proof
\(\ds \int \tanh x \rd x\) | \(=\) | \(\ds \map \ln {\cosh x} + C\) | Primitive of $\tanh x$ | |||||||||||
\(\ds \leadsto \ \ \) | \(\ds \int \tanh a x \rd x\) | \(=\) | \(\ds \frac 1 a \paren {\map \ln {\cosh a x} } + C\) | Primitive of Function of Constant Multiple | ||||||||||
\(\ds \) | \(=\) | \(\ds \frac {\map \ln {\cosh a x} } a + C\) | simplifying |
$\blacksquare$
Also see
- Primitive of $\sinh a x$
- Primitive of $\cosh a x$
- Primitive of $\coth a x$
- Primitive of $\sech a x$
- Primitive of $\csch a x$
Sources
- 1968: Murray R. Spiegel: Mathematical Handbook of Formulas and Tables ... (previous) ... (next): $\S 14$: Integrals involving $\tanh a x$: $14.604$
- 1968: George B. Thomas, Jr.: Calculus and Analytic Geometry (4th ed.) ... (previous) ... (next): Back endpapers: A Brief Table of Integrals: $123$.