[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
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