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x+sqrt(x)

Limit of the function x+sqrt(x)

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 lim \x + \/ x /
x->oo           
$$\lim_{x \to \infty}\left(\sqrt{x} + x\right)$$
Limit(x + sqrt(x), x, oo, dir='-')
Detail solution
Let's take the limit
$$\lim_{x \to \infty}\left(\sqrt{x} + x\right)$$
Let's eliminate indeterminateness oo - oo
Multiply and divide by
$$\sqrt{x} - x$$
then
$$\lim_{x \to \infty}\left(\sqrt{x} + x\right)$$
=
$$\lim_{x \to \infty}\left(\frac{\left(\sqrt{x} - x\right) \left(\sqrt{x} + x\right)}{\sqrt{x} - x}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{\left(\sqrt{x}\right)^{2} - \left(- x\right)^{2}}{\sqrt{x} - x}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{- x^{2} + x}{\sqrt{x} - x}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{- x^{2} + x}{\sqrt{x} - x}\right)$$

Let's divide numerator and denominator by sqrt(x):
$$\lim_{x \to \infty}\left(\frac{- x^{\frac{3}{2}} + \sqrt{x}}{1 - \sqrt{x}}\right)$$ =
$$\lim_{x \to \infty}\left(\frac{- x^{\frac{3}{2}} + \sqrt{x}}{1 - \sqrt{x}}\right)$$ =
$$\lim_{x \to \infty}\left(\frac{- x^{\frac{3}{2}} + \sqrt{x}}{1 - \sqrt{x}}\right)$$
Do replacement
$$u = \frac{1}{x}$$
then
$$\lim_{x \to \infty}\left(\frac{- x^{\frac{3}{2}} + \sqrt{x}}{1 - \sqrt{x}}\right)$$ =
$$\lim_{u \to 0^+}\left(\frac{- \left(\frac{1}{u}\right)^{\frac{3}{2}} + \sqrt{\frac{1}{u}}}{1 - \sqrt{\frac{1}{u}}}\right)$$ =
= $$\frac{\sqrt{\frac{1}{0}} - \left(\frac{1}{0}\right)^{\frac{3}{2}}}{1 - \sqrt{\frac{1}{0}}} = \infty$$

The final answer:
$$\lim_{x \to \infty}\left(\sqrt{x} + x\right) = \infty$$
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
Rapid solution [src]
oo
$$\infty$$
Other limits x→0, -oo, +oo, 1
$$\lim_{x \to \infty}\left(\sqrt{x} + x\right) = \infty$$
$$\lim_{x \to 0^-}\left(\sqrt{x} + x\right) = 0$$
More at x→0 from the left
$$\lim_{x \to 0^+}\left(\sqrt{x} + x\right) = 0$$
More at x→0 from the right
$$\lim_{x \to 1^-}\left(\sqrt{x} + x\right) = 2$$
More at x→1 from the left
$$\lim_{x \to 1^+}\left(\sqrt{x} + x\right) = 2$$
More at x→1 from the right
$$\lim_{x \to -\infty}\left(\sqrt{x} + x\right) = -\infty$$
More at x→-oo
The graph
Limit of the function x+sqrt(x)