MHB Is it possible to prove the inequality without using induction?

Click For Summary
The discussion revolves around proving the inequality $\dfrac{1}{2} \cdot \dfrac{3}{4} \cdot \dfrac{5}{6} \cdots \dfrac{1997}{1998} >\dfrac{1}{1999}$ without using induction. Participants express admiration for the elegant solution provided by a user named Ackbach. The challenge lies in finding a non-inductive approach to demonstrate the inequality's validity. The conversation highlights the complexity of the problem and the satisfaction of discovering a solution. Overall, the thread showcases a successful mathematical exploration of inequalities.
anemone
Gold Member
MHB
POTW Director
Messages
3,851
Reaction score
115
Show that $\dfrac{1}{2} \cdot \dfrac{3}{4} \cdot \dfrac{5}{6} \cdots \dfrac{1997}{1998} >\dfrac{1}{1999}$, where the use of induction method is not allowed.
 
Mathematics news on Phys.org
This is equivalent to showing
$$1 \cdot 3 \cdot 5 \cdot \dots \cdot 1999 > 2 \cdot 4 \cdot 6 \cdot \dots \cdot 1998.$$
But this is so, since $3>2$, and $5>4$, etc. The left-hand product has one more term (the number $1$) in it than the right-hand term. Therefore, the left-hand product is greater.
 
Wow...the moment I saw this problem, I naturally perceived as a hard to prove sort of inequality problem but you cracked it in such an elegant method! Well done, Ackbach, and thanks for participating! :)
 
I have been insisting to my statistics students that for probabilities, the rule is the number of significant figures is the number of digits past the leading zeros or leading nines. For example to give 4 significant figures for a probability: 0.000001234 and 0.99999991234 are the correct number of decimal places. That way the complementary probability can also be given to the same significant figures ( 0.999998766 and 0.00000008766 respectively). More generally if you have a value that...

Similar threads

Replies
1
Views
1K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
2
Views
1K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K