Applicare la formula: $\frac{a^m}{a^n}$$=a^{\left(m-n\right)}$, dove $a^n=e^{\cos\left(x\right)}$, $a^m=e^{5x}$, $a=e$, $a^m/a^n=\frac{e^{5x}}{e^{\cos\left(x\right)}}$, $m=5x$ e $n=\cos\left(x\right)$

Applicare la formula: $\lim_{x\to c}\left(a\right)$=indeterminate, dove $a=e^{\left(5x-\cos\left(x\right)\right)}$, $c=\infty $ e $x->c=x\to\infty $