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Is-the-sequence-u-n-cos-npi-20-divergent-




Question Number 98986 by Ar Brandon last updated on 17/Jun/20
Is the sequence u_n =cos(((nπ)/(20))) divergent?
$$\mathrm{Is}\:\mathrm{the}\:\mathrm{sequence}\:\mathrm{u}_{\mathrm{n}} =\mathrm{cos}\left(\frac{\mathrm{n}\pi}{\mathrm{20}}\right)\:\mathrm{divergent}? \\ $$
Answered by maths mind last updated on 17/Jun/20
u_(40n+10) =0  u_(40n) =1  ⇒u_n  has no limite
$${u}_{\mathrm{40}{n}+\mathrm{10}} =\mathrm{0} \\ $$$${u}_{\mathrm{40}{n}} =\mathrm{1} \\ $$$$\Rightarrow{u}_{{n}} \:{has}\:{no}\:{limite} \\ $$
Commented by Ar Brandon last updated on 18/Jun/20
thanks
$$\mathrm{thanks} \\ $$

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