Geometric Sequences

Which formula is used to find the recursive 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 a recursive formula for the following sequence:

16,8, 4, 2,...

• a₁=16

  a_n=a_n-1 (2)

• a₁=16

  a_n=a_n-1 (1/2)

• a₁=16

  a_n=a_n-1 + (1/2)

• a₁=16

  a_n=a_{n-1 +} (2)

The EXPLICIT formula for a

GEOMETRIC SEQUENCE is

Write the explicit formula for the sequence given by 3, 6, 12, 24, …

• ^a_n= 3(2)^n-1

• ^a_n= 3+(2)ⁿ

• ^a_n= 3(2)ⁿ

• ^a_n= 3+(2)^n-1

What is a₅ in the sequence defined as follows?

a_n = 5 ⋅ 2^(n-1)

• a₅ = 160

• a₅ = 40

• a₅ = 10

• a₅ = 80

Write the explicit formula for the geometric sequence.

• a_n = 4(3)^n-1
• a_n = 3(4)^n-1
• a_n = -4(3)^n-1
• a_n = 3(-4)^n-1

Find the first four terms of the sequence given the rule:
a_n = 4(5)^n-1

• 20, 100, 500, 2500
• 5, 20, 80, 320
• 4, 20, 100, 500
• 4, 9, 14, 19

What does r represent?

• Radical

• Common difference

• Common ratio

What are the next 3 terms in the following geometric sequence:

512, 256, 128, ___, ___, ___, ...

• 1024, 2048, 4096

• 32, 8, 2

• 64, 32, 16

• 92, 66, 38

Is the sequence 2, 4, 12, 48,... geometric?

• yes
• no