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Working out the Nth term of a sequence

nth term

1

2

3

4

5Original number

1

5

9

13

17Difference between each term

4

4

4

4

Working out the Nth term of a sequence

nth term

1

2

3

4

5Original number

1

5

9

13

17Difference between each term

4

4

4

4

To work out the Nth term of a sequence, firstly you neeed to find the difference between the numbers in the sequence, in this sequence shown here the difference between them is +4, so when you know this, you know the first part of the Nth term, that is 4n, to work out the next part of the sequence, you need to work out how much you have to minus to get from 4 to 1, that is 3, so the nth term formula for this is 4n-3

Now for is you want to work out the 20th term in the sequence, you simply replace the letter N, with 20, if your looking for the 20th term, so now the formula says 4 20-3

Now you have this you have to work out 4X20 that is 80 then -3 that gets to 77, this is the 20th term of the sequence

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