Arithmetic & Geometric Sequences

Identify if the sequence is arithmetic, geometric or neither:

-2.5, -5, -10, -20, -40,...

• Arithmetic

• Geometric

• Neither

What is the common ratio of the geometric sequence:

2,10,50,250,1250,...

Identify if the sequence is arithmetic, geometric or neither:

3, 6, 18, 72, 360,...

• Arithmetic

• Geometric

• Neither

Identify if the sequence is arithmetic, geometric or neither:

1,3,9,27, 81,...

• Arithmetic

• Geometric

• Neither

Identify if the sequence is arithmetic, geometric or neither:

4,8,12,16,20,...

• Arithmethic

• Geometric

• Neither

Find the next three terms, given:

1st term: 125

Common ratio: 6

• 750, 4500, 27000

• 750, 5250, 42000

• 750, 3750, 22500

What are the next three terms, given:

1st term = 23

Common ratio = 6

Which formula is used to find the explicit equation for geometric sequences?

• a_n = a_n-1 + d
• a_n = a_n-1 * r
• a_n = a₁ + d(n-1)
• a_n = a₁ * r^n-1

Write an explicit rule for the general term of the sequence 5, 15, 45, . . . ?

• a_n = a_n-1 x 3
• a_n = 5(3)^n-1
• a_n = 3(5)^n-1
• a_n = 5 + (n-1)3

What does r represent?

• Radical

• Common difference

• Common ratio