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Mathematics 16 Online
OpenStudy (junyang96):

Does the limit x-> infinity cos x exists?

OpenStudy (junyang96):

or sin x or tan x

hartnn (hartnn):

what are the possible values cos x can take ?

hartnn (hartnn):

in other words, whats the range of cos x ?

OpenStudy (junyang96):

I am not sure but I don't know if the limit exist

OpenStudy (junyang96):

can't solve this the answer is 2

hartnn (hartnn):

see, when x is a really large number, we say that \(x \to \infty\) and cos of x can be any finite number between -1 and 1, because thats the range of cos

hartnn (hartnn):

so you can reason out this way, cos x/x lim x-> infinity cos x will be a number between -1 to 1 lim x-> infinity 1/x = 0 so, limit x->infinity cos x/x = a finite numer times 0 = 0

hartnn (hartnn):

your numerator then, will be just 2+0

hartnn (hartnn):

and denominator is easily (1+0)^2 =1 as x->infinity, 1/x ->0 hence 2/x =0

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