Geometric Sequences: obtained by multiplying
the preceeding term by a common ratio (r)
If x1, x2, x3, ... is a geometric sequence with common ratio r, then r = x2 = x3 = x4
x1 x2 x3
3, 6, 12, 24
Whats the common ratio?
1
Determine whether the sequence is geometric. If it is, find r. a. ­2, ­10, ­50, ­250, ...
b. 2, 4, 6, 8, ...
2
Write the next three terms of the geometric sequence 64, ­32, 16, ­8, ...
3
Write the first four terms of the geometric sequence whose first term a1 is ‐3 and whose common ratio r is ‐4.
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nth term of a geometric sequence
an = (a1)( rn­1)
Find the specified term of each geometric sequence
a. 5th term, a1=7, r = 0.2
b. 10th term of ­8, 4, ­2, ...
5
Homework: pg 560 #1­17odd
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