Given the question lim
I have deducted so far that this has the indeterminate form 0^0 so I have taken the natural logarithm of both sides to give me: \lim_{x\to0^+} \ln(y) = \lim_{x\to0^+}\sin(x)\ln(x) This still has an indeterminate form so I rearrange it to start using L'hospitals rule: \lim_{x\to0^+}\frac{\ln(x)}{\csc(x)} =\lim_{x\to0^+}\frac{\frac1x}{-\csc(x)\cot(x)} =\lim_{x\to0^+}\frac{-\sin(x)\tan(x)}{x} =\lim_{x\to0^+}\frac{-\cos(x)\sec^2(x)}{1} = -1 \lim_{x\to0^+}x^{\sin(x)} = \frac1e
I don't think this is correct, am I doing something wrong, and if so, where?
Answer
\lim_{x\to0^+} x^{\sin(x)}
=\lim_{x\to0^+} \exp(\ln(x)\sin(x))
=\exp(\lim_{x\to0^+} \ln(x)\sin(x))
=\exp(\lim_{x\to0^+} \frac{\ln(x)}{1/\sin(x)})
Applying L'Hôpital's rule:
=\exp(\lim_{x\to0^+} -\frac{\sin(x)^2}{x\cos(x)})
=\exp(-1\cdot \lim_{x\to0^+} \frac{1}{\cos(x)}\lim_{x\to0^+} \frac{\sin(x)^2}{x})
=\exp(-\lim_{x\to0^+} \frac{\sin(x)^2}{x})
Applying L'Hôpital's rule:
=\exp(-\lim_{x\to0^+} 2\cos(x)\sin(x))
\color{grey}{e^0=1}
=\boxed {\color{blue}1}
No comments:
Post a Comment