00:01
In part a, we are to expand this summation.
00:04
I starts from 5 and ends at 8.
00:07
So when i is 5, we have a5x5.
00:14
Plus, when i is 6, we have a6x6.
00:19
And when i is 7, we have a7x7.
00:24
And when i is 8, we have a8x8.
00:29
So this is the fully expanded for the summation.
00:33
Part b, i runs from 1 to 4.
00:37
So i will have for the i is 1, i have bx1.
00:42
Plus, when i is 2, i have bx2.
00:46
When i is 3, bx3.
00:49
When i is 4, we have bx4.
00:52
Now, this b is constant, so it can be factorized.
00:58
And so we have b bracket x1 plus x2 plus x3 plus x4.
01:07
Now, part c, i runs from 1 to n.
01:15
And this part here is i minus 1...