13-1

On Thursday, we started learning chapter 13-1. Unfortunately I wasn’t there for 7th hour that day so I had to try and catch up on this section Friday. It didn’t work out too well and I am not very sure what we are doing. I have been trying to teach myself, but I feel like I need a review in class on Monday. Since I am still kind of lost, I’ll show an example of some easy problems that I can do on my own.

Chapter 13-1 is about finding arithmetic and geometric sequences. The first thing that is usually asked is for you to identify.

Arithmetic- when the sequence of numbers has the same number added to them. The formula is:
tn= t1 + (n – 1) (d)

Geometric- when the sequence of numbers has the same number multiplied to them. The formula is:
tn= t1 x r^n -1

Examples:


1.State whether it is arithmetic or geometric.
1, 2, 4, 8, 16
Answer would be geometric because 2 is being multiplied.

2. How many multiples of 5 are there between 30 and 525?
The sequence is: 30, 35, 40, 45,…..525
The numbers are being added, so you use the arithmetic formula.
525 = 30 + (n-1) (5)
525 = 30 + 5n – 5
525 = 25 + 5n
500 = 5n
N = 100