[Week 1]- Arithmetic Sequences

What I have learned:

- what is arithmetic sequences and common different.
- How to find common different.
- How to calculate the sum of n term of an arithmetic series
- Use a rule to determine t1 and d in an arithmetic sequence given the values of tn and n.
- Use a rule to determine tn and n in an arithmetic sequence given the values of t1 and d.
- Use a rule to determine the sum Sn of an arithmetic series.

Ex. Use the arithmetic series, determine the indicated value.

1 + 3.5 + 6 + 8.5 + …; determine S42.

Know: Sn = n/2 [2 t1 + d (n-1)]

T1 = 1 = 42/2[2+2.5*41]

T2= 3.5 = 2194.5

d= 2.5

Ex. Use the giving data to determine the indicated value.

S20 = -850 and t20 = -90; determine t1

Sn = n/2 (t1 +tn)

-850 = 20/2[t1 +(-90)]

10 t1 = 50

t 1 = 5

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