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Known-a-R-and-function-f-R-R-satiesfied-xf-x-a-lt-sin-2-x-a-For-all-x-R-value-of-lim-x-a-f-x-




Question Number 55639 by gunawan last updated on 01/Mar/19
Known a ∈ R and  function f : R→R satiesfied  ∣xf(x)+a∣ < sin^2  (x−a).   For all x ∈ R  value of lim_(x→a)  f(x) ..
KnownaRandfunctionf:RRsatiesfiedxf(x)+a<sin2(xa).ForallxRvalueoflimxaf(x)..
Answered by kaivan.ahmadi last updated on 01/Mar/19
−sin^2 (x−a)<xf(x)+a<sin^2 (x−a)  by sandwich theorem  lim_(x→a) xf(x)+a=0⇒lim_(x→a)  xf(x)=−a⇒  lim_(x→a) x×lim_(x→a) f(x)=−a⇒  lim_(x→a) f(x)=−1
sin2(xa)<xf(x)+a<sin2(xa)bysandwichtheoremlimxfxa(x)+a=0limxaxf(x)=alimxxa×limfxa(x)=alimfxa(x)=1

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