00:01
We're being asked to find the sum of the series that's given to us in sigma notation.
00:05
So first thing we're going to do is we're going to find a sub 1, the first term.
00:08
To do this, we're going to substitute 1 in place of n.
00:12
So we're going to have 3 minus 2 times 1.
00:15
Well, 2 times 1 is 2 and 3 minus 2 is 1.
00:18
So our first term is 1.
00:21
Next, we're going to find a sub n.
00:23
To do this, we're going to substitute 90 in place of n.
00:27
So we're going to have 3 minus 2 times 90.
00:30
Well, 2 times 90 is equal to 180, and 3 minus 180 is equal to negative 177...