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Mathematics 9 Online
OpenStudy (mortonsalt):

Limit question! Will be posted below.

OpenStudy (mortonsalt):

\[\lim_{x \rightarrow 0^+} 3\sqrt{x}lnx\]

OpenStudy (freckles):

have you tried writing it as a quotient and see if l'hospital applies

OpenStudy (mortonsalt):

I tried getting the derivative of it. But the answer key says the answer 0, and I'm not entirely sure why. @freckles

OpenStudy (mortonsalt):

Getting the derivative and applying l'hospital's*

OpenStudy (freckles):

let's just ignore the 3 part for now

OpenStudy (freckles):

\[\lim_{x \rightarrow 0^+} \frac{\ln(x)}{\frac{1}{x^\frac{1}{2}}}\]

OpenStudy (freckles):

here we have -inf/inf so we can use l'hospital

OpenStudy (freckles):

the derivative of ln(x) w.r.t. x is ? the derivative of 1/(x^(1/2)) is w.r.t. x is?

OpenStudy (mortonsalt):

1/x and -0.5sqrtx ?

OpenStudy (freckles):

\[\frac{d}{dx}(\frac{1}{x^{\frac{1}{2}}})=\frac{d}{dx}(x^{-\frac{1}{2}})=-\frac{1}{2}x^{\frac{-1}{2}-1}=\frac{-1}{2}x^{\frac{-3}{2}}=\frac{-1}{2 x^{\frac{3}{2}}}\]

OpenStudy (freckles):

\[l im_{x \rightarrow 0^+}\frac{\frac{1}{x}}{\frac{-1}{2 x^{\frac{3}{2}}}} \\ =\lim_{x \rightarrow 0^+} \frac{1}{x} \cdot \frac{2x^{\frac{3}{2}}}{-1} \]

OpenStudy (mortonsalt):

Oh my god, careless mistakes. I get it now. Thank you! @freckles

OpenStudy (freckles):

np

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