00:01
In this problem, we're being asked to find the sum of this given geometric series.
00:05
Well, remember, the formula to find the sum is s sub n is equal to a sub 1 times the quantity of 1 minus r to the n power all over 1 minus r.
00:17
Well, in this particular series, we know a sub 1 is just the first term, which is 1 half.
00:23
We also know r.
00:24
That's the constant that's getting multiplied to go from one term to the next, which in this case is negative 1⁄2.
00:31
And we also know n because there are 1, 2, 3, 4, 5 terms in this series.
00:37
So n is equal to 5.
00:39
So we just need to substitute these values into our formula.
00:42
So we'll have s of 5 equals a sub 1, which is 1 1⁄2, times the quantity of 1 minus r, which is negative 1⁄2, raised to the 5th power, and it's all getting divided by 1 minus r, which is negative 1 .5...