Examples of Derivative of Hyperbolic Functions

Example: Differentiate {x^3}{\tanh ^2}\sqrt x with respect to x.

Consider the function

y  = {x^3}{\tanh ^2}\sqrt x

Differentiate both sides with respect to x, we have

\frac{{dy}}{{dx}}  = \frac{d}{{dx}}{x^3}{\tanh ^2}\sqrt x


Using product rule of differentiation, we have

\begin{gathered} \frac{{dy}}{{dx}} = {\tanh ^2}\sqrt x  \frac{d}{{dx}}{x^3} + {x^3}\frac{d}{{dx}}{\tanh ^2}\sqrt x \\ \Rightarrow \frac{{dy}}{{dx}} = {\tanh  ^2}\sqrt x \left( {3{x^2}} \right) + {x^3}\left( {2\tanh \sqrt x  \frac{d}{{dx}}\tanh \sqrt x } \right) \\ \Rightarrow \frac{{dy}}{{dx}} = 3{x^2}{\tanh  ^2}\sqrt x + {x^3}2\tanh \sqrt x \sec  {{\text{h}}^2}\sqrt x \frac{d}{{dx}}\sqrt x \\ \Rightarrow \frac{{dy}}{{dx}} = 3{x^2}{\tanh  ^2}\sqrt x + 2{x^3}\tanh \sqrt x \sec  {{\text{h}}^2}\sqrt x \frac{1}{{2\sqrt x }} \\ \Rightarrow \frac{{dy}}{{dx}} = 3{x^2}{\tanh  ^2}\sqrt x + {x^3}\tanh \sqrt x \sec  {{\text{h}}^2}\sqrt x \frac{1}{{\sqrt x }} \\ \Rightarrow \frac{{dy}}{{dx}} = 3{x^2}{\tanh  ^2}\sqrt x + {x^{\frac{5}{2}}}\tanh  \sqrt x \sec {{\text{h}}^2}\sqrt x \\ \end{gathered}

Example: Find \frac{{dy}}{{dx}}, if the given function is

y = \sinh \left( {\cos 3x}  \right)

 We have the given function

y =  \sinh \left( {\cos 3x} \right)

Differentiate both sides with respect to x, we have

\begin{gathered} \frac{{dy}}{{dx}} = \frac{d}{{dx}}\sinh  \left( {\cos 3x} \right) \\ \Rightarrow \frac{{dy}}{{dx}} = \cosh \left(  {\cos 3x} \right)\frac{d}{{dx}}\cos 3x \\ \Rightarrow \frac{{dy}}{{dx}} = \cosh \left(  {\cos 3x} \right)\left( { - \sin 3x} \right)\frac{d}{{dx}}3x \\ \Rightarrow \frac{{dy}}{{dx}} = \cosh \left(  {\cos 3x} \right)\left( { - \sin 3x} \right)\left( 3 \right) \\ \Rightarrow \frac{{dy}}{{dx}} = - 3\cosh \left( {\cos 3x} \right)\sin 3x \\ \end{gathered}

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