Friday, April 3, 2015

solve the limit of the function f(x)=sin5x/sinx if x --> pi

We have to find the value of lim x--> pi[ sin 5x /
sin x]


We see that substituting x with pi gives us the form
0/0 which is indeterminate. We can use therefore use l'Hopital's rule and use the
derivative of the numerator and the denominator


lim
x--> pi [sin 5x / sin x]


=> lim x-->
pi [ 5* cos 5x / cos x]


substtuting x = pi , now
gives


(5*-1)/ (-1)


=>
5


The required value of lim x--> pi[
sin 5x / sin x] is 5.

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