[tex]\large \bold {SOLUTION}[/tex]
[tex]\large\sf{y = ln( \cosh(2x) ) }[/tex]
[tex]\small\textsf{By the Chain Rule of differentiation, let u = cosh (2x)}[/tex]
[tex]\small\sf{(f[g(x)])' = f'[g(x)] \: \: • \: \: g'(x)}[/tex]
[tex]\small\sf{y' = \dfrac{d}{du} \: ln(u) \: \:• \: \: \dfrac{d}{dx} \: \cosh(2x) }[/tex]
[tex]\small\textsf{Set aside the first term and differentiate the second term}[/tex]
[tex]\small\textsf{By the Chain Rule of differentiation, let u = 2x}[/tex]
[tex]\small\sf{ \dfrac{d}{du} \: \cosh(u) \: \: • \: \: \dfrac{d}{dx} \: 2x }[/tex]
[tex]\small\sf{y' = \dfrac{d}{du} \: ln(u) \: \: • \: \: \sinh(u) \: \: • \: \: 2 }[/tex]
[tex]\small\textsf{Return u = 2x as the substitution}[/tex]
[tex]\small\sf{y' = \dfrac{d}{du} \: ln(u) \: \: • \: \: \sinh(2x) \: \: • \: \: 2 }[/tex]
[tex]\small\sf{y' = \dfrac{1}{u} \: \: • \: \: \sinh(2x) \: \: • \: \: 2 }[/tex]
[tex]\small\textsf{Return the main u-substitution}[/tex]
[tex]\small\sf{y' = \dfrac{1}{ \cosh(2x) } \: \: • \: \: \sinh(2x) \: \: • \: \: 2 }[/tex]
[tex]\small\sf{y' = \dfrac{1}{ \cosh(2x) } \: \: • \: \: 2\sinh(2x) }[/tex]
[tex]\therefore\small\sf{y' = ln( \cosh(2x) ) \implies\small\boxed{\green{\sf{ \frac{2 \sinh(2x) }{ \cosh(2x) } }}}}[/tex]
[tex]\small\textsf{\#AlwaysBeTheGreat}[/tex]
