Menu Close

If-f-x-x-sin-1-x-where-x-0-then-find-the-value-of-function-at-x-0-and-given-that-function-is-continuous-at-x-0-




Question Number 77533 by vishalbhardwaj last updated on 07/Jan/20
If f(x)=x sin((1/x)) where x≠0  then find the value of function at x=0  and given that function is continuous at x=0 ?
$$\mathrm{If}\:\mathrm{f}\left(\mathrm{x}\right)=\mathrm{x}\:\mathrm{sin}\left(\frac{\mathrm{1}}{\mathrm{x}}\right)\:\mathrm{where}\:\mathrm{x}\neq\mathrm{0} \\ $$$$\mathrm{then}\:\mathrm{find}\:\mathrm{the}\:\mathrm{value}\:\mathrm{of}\:\mathrm{function}\:\mathrm{at}\:\mathrm{x}=\mathrm{0} \\ $$$$\mathrm{and}\:\mathrm{given}\:\mathrm{that}\:\mathrm{function}\:\mathrm{is}\:\mathrm{continuous}\:\mathrm{at}\:\mathrm{x}=\mathrm{0}\:? \\ $$
Answered by MJS last updated on 07/Jan/20
lim_(x→0)  xsin (1/x) =       [let x=(1/t)]  =lim_(t→±∞)  ((sin t)/t) =0  ⇒ f(0)=0
$$\underset{{x}\rightarrow\mathrm{0}} {\mathrm{lim}}\:{x}\mathrm{sin}\:\frac{\mathrm{1}}{{x}}\:= \\ $$$$\:\:\:\:\:\left[\mathrm{let}\:{x}=\frac{\mathrm{1}}{{t}}\right] \\ $$$$=\underset{{t}\rightarrow\pm\infty} {\mathrm{lim}}\:\frac{\mathrm{sin}\:{t}}{{t}}\:=\mathrm{0} \\ $$$$\Rightarrow\:{f}\left(\mathrm{0}\right)=\mathrm{0} \\ $$
Commented by vishalbhardwaj last updated on 07/Jan/20
thanks a lot sir

Leave a Reply

Your email address will not be published. Required fields are marked *