00:01
Okay, so in this question, we're asked to calculate three different sums, and we're given some information in the beginning of the problem that's going to allow us to do this.
00:07
So we're given that a sub 1 is equal to negative 5.
00:11
We're given that the sum from i equals 1 to 10 of a sub i is equal to 20.
00:16
And we're also given that the sum from i equals 1 to 10 of b sub 1 is equal to 7.
00:21
So first let's do a.
00:26
In part a, we have to find the sum from 1 to 10 of 4a sub i plus 3.
00:32
So what we can do is we can break that up into two separate sums.
00:35
So that's going to be equivalent to four times the sum from i is equal to 1 to 10 of a sub i.
00:47
And we can just move this constant in and out of the sum.
00:50
It doesn't change that value.
00:54
Plus the sum from i equals 1 to 10 of 3.
01:04
So this value we already know, we're in the problem we're given that this is 20...