Arithmetic and Geometric Sequences Review with Explicit Formulas

Find the first term in the arithmetic sequence where the 6th term is 56 and the 9th term is 92.

• -16

• 12

• -4

• 8

How many terms are in the series where the first term is 4, d=3, and S_n=11,309?

• 191,868,494

• 85

• 86

• 640

Find S₂₀ for the given series with a₁=3 and r=-2.

• 3,145,725

• -320

• 1,048,575

• -1,048,575

Find S₁₀ for the series that begins 48+24+12+...

• 49,104

• 3069/32

• 1005/2

• 1023/32

Insert 3 arithmetic means in the sequence 10, ___, ___, ___, 130.

• 40, 70, 100

• 30, 60, 90

• 50, 80, 110

• 20, 60, 120

Given the sequence: 25, 21, 17, 13,... Write the explicit formula that models the sequence.

• a_n = 25 + (n - 1)(4)

• a_n = 25 + (n - 1)(-4)

• a_n = 25(-4)^n-1

• a_n = 25 + (n - 1) - 4

Which kind of sequence has a common ratio?

• Arithmetic

• Geometric

Find the sum 
24+48+72+...+480

• 5280

• 9576

• 10080

• 5040

What is the twelfth term in the sequence 3, -6, 12, . . . ?

• -2,048

• 6,144

• -6,144

• -531,441

Find the explicit formula for: 64, -32, 16, -8, …

• a_n=64(1/2)^n-1

• a_n=64 + (n-1)(-1/2)

• a_n=64(-1/2)^n-1

• a_n=(32)^n-1