00:01
Hi, in the question we need to prove that we have sum to n terms of geometric series in positive terms greater than n times geometric mean of the first and n -f term of the rules.
00:10
So we just work on this plus minus sum to n terms to the geometric series with positive terms.
00:15
So given as a plus a r plus a square and con plus a r with the power n negative one.
00:23
Here we have a and r are positive.
00:28
So this is not a set of numbers we have a number.
00:32
A r, a .r square and so on till a r to the part n negative 1 is positive.
00:38
That is given.
00:40
So we know that arithmetic mean, so a and r both are positive.
00:45
That means it's an increasing gp.
00:47
It's an increasing gp, so arithmetic mean cannot be equal to gm.
00:50
So we have arithmetic mean is greater than g.
00:52
This relation, standard result we're going to use here.
00:55
So we get a plus.
00:57
Why we're not taking equal to? because r is positive, right? because it's an increasing gp...