Geometric Arithmetic Sequences

What is the common ratio of the geometric sequence below?
5, 25, 125, 625...

• 25

• 20

• 5

• 4

What is the 8th term in the geometric sequence below?

• 19,683

• 6,561

• 2,187

• 729

What is the common ratio of this geometric sequence?

500, 200, 80, 32, ...

• -5/2

• -2/5

• 2/5

• 5/2

Which sequence is a geometric sequence with a common ratio of 2?

• 5, 3, 1, -1, ...

• 5, 7, 9, 11, ...

• 5, 10, 20, 40, ...

• 5, 15, 45, 135, ...

• Arithmetic

• Geometric

Answer explanation

Percentages are almost always Geometric.

In a geometric sequence, a₁ = 486 and a₂ = 162. What is the explicit formula for this sequence?

• a_n = 2(3)^n-1

• a_n = 18(3)^n-1

• a_n = 18(1/3)^n-1

• a_n = 486(1/3)^n-1

• Arithmetic

• Geometric

• Neither

• Both

Which of the following best describes this sequence?

• A geometric sequence with a common difference of 3.

• An arithmetic sequence with a common difference of 3.

What is a₅ for the sequence below?

a_n = 5 ⋅ 2^(n-1) 

• a₅ = 160

• a₅ = 40

• a₅ = 10

• a₅ = 80

What is the explicit rule for the sequence? 11, 22, 44, 88...

• a_n = 2(11)^n-1

• a_n = 11(2)

• a_n = 11(2)^n-1