
Andy C. answered 11/02/17
Tutor
4.9
(27)
Math/Physics Tutor
You can prove it by contradiction.
Suppose there is another least upper bound T , not equal to 1,such that
1-1/N < T< 1 for n=1,2,3,....
Taking the limit as n tends to infinity of all three sides forces T =1 by sandwich theorem.