Prove that:
$$\Big|x\sin\Big(\frac{1}{x}\Big)-y\sin\Big(\frac{1}{y}\Big)\Big|\leq\sqrt{2|x-y|}$$
My attempt
I have prove that $$F(x,y)=\frac{f(x)-f(y)}{|x-y|^a}$$ $$f(x)=x\sin\Big(\frac{1}{x}\Big)$$have a bound if and only if $a\leq\frac{1}{2}$.
But I can't prove that $F(x)\leq\sqrt2$, if $a=\frac{1}{2}$.
So I want to get some help. Thank you.
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