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(1+7/x)^(x/3)

Limit of the function (1+7/x)^(x/3)

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The solution

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            x
            -
            3
     /    7\ 
 lim |1 + -| 
x->oo\    x/ 
$$\lim_{x \to \infty} \left(1 + \frac{7}{x}\right)^{\frac{x}{3}}$$
Limit((1 + 7/x)^(x/3), x, oo, dir='-')
Detail solution
Let's take the limit
$$\lim_{x \to \infty} \left(1 + \frac{7}{x}\right)^{\frac{x}{3}}$$
transform
do replacement
$$u = \frac{x}{7}$$
then
$$\lim_{x \to \infty} \left(1 + \frac{7}{x}\right)^{\frac{x}{3}}$$ =
=
$$\lim_{u \to \infty} \left(1 + \frac{1}{u}\right)^{\frac{7 u}{3}}$$
=
$$\lim_{u \to \infty} \left(1 + \frac{1}{u}\right)^{\frac{7 u}{3}}$$
=
$$\left(\left(\lim_{u \to \infty} \left(1 + \frac{1}{u}\right)^{u}\right)\right)^{\frac{7}{3}}$$
The limit
$$\lim_{u \to \infty} \left(1 + \frac{1}{u}\right)^{u}$$
is second remarkable limit, is equal to e ~ 2.718281828459045
then
$$\left(\left(\lim_{u \to \infty} \left(1 + \frac{1}{u}\right)^{u}\right)\right)^{\frac{7}{3}} = e^{\frac{7}{3}}$$

The final answer:
$$\lim_{x \to \infty} \left(1 + \frac{7}{x}\right)^{\frac{x}{3}} = e^{\frac{7}{3}}$$
Lopital's rule
There is no sense to apply Lopital's rule to this function since there is no indeterminateness of 0/0 or oo/oo type
The graph
Other limits x→0, -oo, +oo, 1
$$\lim_{x \to \infty} \left(1 + \frac{7}{x}\right)^{\frac{x}{3}} = e^{\frac{7}{3}}$$
$$\lim_{x \to 0^-} \left(1 + \frac{7}{x}\right)^{\frac{x}{3}} = 1$$
More at x→0 from the left
$$\lim_{x \to 0^+} \left(1 + \frac{7}{x}\right)^{\frac{x}{3}} = 1$$
More at x→0 from the right
$$\lim_{x \to 1^-} \left(1 + \frac{7}{x}\right)^{\frac{x}{3}} = 2$$
More at x→1 from the left
$$\lim_{x \to 1^+} \left(1 + \frac{7}{x}\right)^{\frac{x}{3}} = 2$$
More at x→1 from the right
$$\lim_{x \to -\infty} \left(1 + \frac{7}{x}\right)^{\frac{x}{3}} = e^{\frac{7}{3}}$$
More at x→-oo
Rapid solution [src]
 7/3
e   
$$e^{\frac{7}{3}}$$
The graph
Limit of the function (1+7/x)^(x/3)