Let m and n be two positive integers greater than 1. If lim α → 0 ⁡ e c o s ⁡ ( &#945…

Let m and n be two positive integers greater than 1. If limα0ecos(αn )-eαm= -e2 then the value of mn is

Solution

limα0ecosαn-eαm= -e2
   Using L'Hospital's Rule

limα0ecosαn -sinαn nαn-1m αm-1= -e2
 mn=2 .

Asked in: JEE Advanced 2015 (Paper 2)

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