Sunday, March 4, 2012

13-1

Things you should know:
  • A sequence that is generated by adding the same number each time is called the arithmetic sequence.
  • Formula: tn = t1 + (n-1) x d
  • d = what is being adding/difference
  • tn = blank terms
  • t1 = first term
  • n = term number
  • A sequence that is generated by multiplying the same number each time is called the geometric sequence.
  • Formula: tn = t1 x r^(n-1)
  • r = what is being multiplied
  • n = term number
  • tn = blank terms
  • t1 = first term
  • A sequence is a list of numbers.

Example 1: tn = 6n + 20. What is the sequence? Is it geometric, arithmetic, or neither?

  • First thing you need to know is you plug in the number of terms you want to find out for n.
  • You are going to find out the first four terms.
  • T1 = 6(1) + 20 = 26
  • T2 = 6(2) + 20 = 32
  • T3 = 6(3) + 20 = 38
  • T4 = 6(4) + 20 = 44
  • Now we have to find out what is the sequence.
  • Each time you are adding 6 to get to the next number so that means it is an arithmetic sequence.

Example 2: tn = 5 x 10^n-1. What is the sequence? Is it geometric, arithmetic, or neither?

  • Just like in example one, you have to plug in the number of terms you want to find our for n.
  • You are going to find the first four terms again.
  • T1 = 5 x 10^1-1 = 5 x 10^0 = 5
  • T2 = 5 x 10^2-1 = 5 x 10^1 = 50
  • T3 = 5 x 10^3-1 = 5 x 10^2 = 500
  • T4 = 5 x 10^4-1 = 5 x 10^3 = 5000
  • Now you have to find out the sequence.
  • Each time you are multiplying 10 to get to the next number so that means it is an geometric sequence.

- Amber :)

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