Sunday, 6 January 2013

real analysis - There is some NinBbbZ+ such that |f(xn)|geqfrac|f(x)|2 for all ngeqN

Let f:RR be a continuous function. Let {xn}n=1 be a convergent sequence in R with lim and f(x)\ne 0



I want to prove that there is some N\in\Bbb Z^+ such that |f(x_n)| \geq \frac{|f(x)|}{2} for all n\geq N






I think I should do this by proving that for a continuous f, x_n\to x \implies f(x_n)\to f(x), and then using that to prove the statement.



Is this the correct approach?

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