Q.

limn{(212-213)(212-215)(212-212n+1)} is equal to                  [2023]
 

1 12  
2 1  
3 0  
4 2  

Ans.

(3)

Let  L=limn{(21/2-21/3)(21/2-21/5)(21/2-21/(2n+1))}

By Sandwich Theorem,

(21/2-21/3)n<(21/2-21/3)(21/2-21/5)(21/2-21/7)(21/2-21/(2n+1))<(21/2-21/(2n+1))n

limn(21/2-21/3)n<L<limn(21/2-21/(2n+1))n

As,  limn(21/2-21/3)n=0 and limn(21/2-21/(2n+1))n=0

  L=0