00:01
Suppose we have a series which goes one -fourth, then two -fourths, then two -squared -fourths, and so on, all the way out to sum 2 to the n -minus 1 over 4.
00:13
Let's determine what the sum is equal to.
00:15
Well, according to the chapter, we have this formula in which, if you take the summation from k -equals 1 to sum n of a -1 times r to the k -minus 1, you'll be able to get a1 times 1 minus r to the n over 1 minus r.
00:36
So this is definitely for if you know the first term and the common ratio.
00:41
So we can easily figure these out by using the information given.
00:45
The first term, a1, that's pretty easy.
00:48
It's just one fourth.
00:49
Just the first term.
00:50
The common ratio, we just have to divide two consecutive terms...