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Arithmetic Sequences

YOUR TURN:

Find the difference:

( 9 / 2 ) , ( 43 / 10 ) , ( 41 / 10 ) , ( 39 / 10 ) , ( 37 / 10 ) , ...

OK, now we need to figure out how to get the nth term for these things.

Given this arithmetic sequence

3 , 7 , 11 , 15 , 19 , ...

Let's find the 50th term, the 100th term and the nth term.

First, we need the difference... 4!

Whenever you're trying to create a math formula, it's always a good idea to make a table and look for a pattern.

term: a1 , term value: 3 ... term: a2 , term value: 3 + 4 = 7 ... use a1 ( 3 ) ... and the difference ( 4 )

 

term: a1 , term value: 3 ... term: a2 , term value: 3 + 4 = 7 ... term: a3 , term value: 3 + 4 + 4 = 11 ... term: a4 , term value: 3 + 4 + 4 + 4 = 15 ... keep adding the difference ( 4 )