Re: ISI 2013 ME - I Answer Key

Posted by Ridhika on May 08, 2014; 11:10am
URL: http://discussion-forum.276.s1.nabble.com/ISI-2013-ME-I-Answer-Key-tp7579715p7588991.html

@ Sinistral.. in your explanation for 2..

n(n+1)(2n+1)       1.2 +2.3 +3.4 + ... n(n+1)        (n+1)(n+2)(2n+3) -6 
-------------  <  -------------------------   <   ---------------------
      6n^3                      n^3                                     6n^3      


ratio of coefficients of highest order of n in the numerator and denominator gives the limit of the fraction as n tends to infinity.
which is nothing but 2/6 = 1/3 for both the LHS & RHS terms.
hence option c

What is the condition for using this rule (the part I have italicized?) Do we have to always express as an inequality on both sides to use this?