Sequences Review

The 5th term of an arithmetic sequence is 21 and the 11th term is 51. Find the common difference.

• -10

• -5

• 5

• 10

Write the recursive formula for 6, 17, 28, 39, 50....

• a_n=a_n-1+11
  a₁=6
• a_n=a_n-1-4
  a₁=6
• a_n=a_n-1+9
  a₁=6
• a_n=a_n-1+6
  a₁=6

Which of the following recursive formulas represents the given sequence.

7, 14, 28, 56, 112, ...

Write the explicit equation for the geometric sequence: 15, 45, 135, . . . ?

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

Select the explicit rule that represents the sequence.

Write the explicit rule for this situation.

• f(n) = 35 + 3(n − 1)
• f(n) = 35 −3(n − 1)
• f(n) = 3 + 35(n − 1)
• f(n) = −3 + 35(n − 1)

• 5.5, 6, 6.5, 7

• 5.5, 2.75, 1.375, 0.6875

• -0.5, 5, 10.5, 16

• 5.5, 5, 4.5, 4

Given the sequence -5, -15, -25, -35..., which recursive formula describes it?

• 70

• 75

• 95