Week #17

Arithmetic sequences: The main characteristic of an arithmetic sequence is that the pattern is always the same number and is just addition and subtraction.

The formula is: Tn=T1+(n-1)(d)

T1= The first term

d= Difference

Example: In a sequence 3,8,13,18…..find T18. Where T1 is 3 and T4 is 18

1- Find the difference. We can deduce it or use this formula

d=aj-ai/j-1

aj= The biggest number

ai=Smallest number

j=Biggest position

i=Smallest position

d= 18-3/4-1= 15/3= 5

Finding T18 using the formula

T18= 3+(18-1)(5)

3+85

T18=88

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