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Compute the limit of the given function

Evaluate the limit.

    \[ \lim_{x \to + \infty} \frac{\cosh (x+1)}{e^x}. \]


We recall the definition of the hyperbolic cosine in terms of the exponential,

    \[ \cosh (x+1) = \frac{e^{x+1} + e^{-(x+1)}}{2}. \]

Using this we compute,

    \begin{align*}  \lim_{x \to +\infty} \frac{\cosh(x+1)}{e^x} &= \lim_{x \to +\infty} \frac{e^{x+1} + e^{-(x+1)}}{2e^x} \\[9pt]  &= \lim_{x \to + \infty} \left( \frac{e}{2} + \frac{1}{2e^{2x+1}} \right) \\[9pt]  &= \frac{e}{2}. \end{align*}

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