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Calculate-lim-n-1-2-n-3-n-1-n-




Question Number 162790 by LEKOUMA last updated on 01/Jan/22
Calculate   lim_(n→∞) (1+2^n +3^n )^(1/n)
$${Calculate}\: \\ $$$$\underset{{n}\rightarrow\infty} {\mathrm{lim}}\left(\mathrm{1}+\mathrm{2}^{{n}} +\mathrm{3}^{{n}} \right)^{\frac{\mathrm{1}}{{n}}} \\ $$
Answered by mindispower last updated on 01/Jan/22
=lim_(n→∞) e^((ln(3^n )+ln((1/3^n )+((2/3))^n +1))/n)   =lim_(n→∞) e^(ln(3)) .e^(ln(1+(1/3^n )+((2/3))^n )) =3  (1/3^n )→0,((2/3))^n →0
$$=\underset{{n}\rightarrow\infty} {\mathrm{lim}}{e}^{\frac{{ln}\left(\mathrm{3}^{{n}} \right)+{ln}\left(\frac{\mathrm{1}}{\mathrm{3}^{{n}} }+\left(\frac{\mathrm{2}}{\mathrm{3}}\right)^{{n}} +\mathrm{1}\right)}{{n}}} \\ $$$$=\underset{{n}\rightarrow\infty} {\mathrm{lim}}{e}^{{ln}\left(\mathrm{3}\right)} .{e}^{{ln}\left(\mathrm{1}+\frac{\mathrm{1}}{\mathrm{3}^{{n}} }+\left(\frac{\mathrm{2}}{\mathrm{3}}\right)^{{n}} \right)} =\mathrm{3} \\ $$$$\frac{\mathrm{1}}{\mathrm{3}^{{n}} }\rightarrow\mathrm{0},\left(\frac{\mathrm{2}}{\mathrm{3}}\right)^{{n}} \rightarrow\mathrm{0} \\ $$

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