Geometric Series Review

Find the common ratio: 4, -16, 64, -256, ...

• r = -4

• r = 2

• r = -2

• r = 4

What is the common ratio for the following sequence: -3, 15, -75, 375, ...

• 12

• -1/5

• -5

• 3

If the rule for finding a_n of a geometric sequence is

a_n = 10(2)^n-1 _{. Then what is the common ratio(r) of the sequence?}

• ²

• ¹⁰

• ²⁰

• 2ⁿ

What is the 9^th term in a geometric sequence with a common ratio of 2 and a first term of 3?

• 384

• 768

• 1,536

• 27

What is the twelfth term in the sequence 3, -6, 12, -24. . . ? (hint: write the general rule and then find the term when n=12)

• -2,048

• 6,144

• -6,144

• -531,441

Write the general rule for the geometric sequence 5, 45, 405, ...?

• a_n = a_n-1 x 5

• a_n = 5(9)^n-1

• a_n = 9(5)^n-1

• a_n = 5 + (n-1)9

What is the general rule for the geometric sequence where the 8th term is 6,561 and r = 3?

Evaluate the geometric series described.

3+15+75+375+..., n=6

• 11,718

• 9,769

• 10,603

• -3/4

Evaluate the geometric series

1-2+4-8..., n=8

• 1/3

• -87

• -86

• -85