Arithmetic Sequences and Series

-21, -16, -11, -6, ...

Is this sequence arithmetic, geometric, or neither?

• arithmetic (common difference d = 5)

• geometric (common ratio r = 5)

• neither

Find the 25th term of the sequence if a₁ = 5 and d = 0.5

• 18

• 17

• 15

• 14

Find the 35th term in the arithmetic sequence: -10, -14, -18, -22, ...

• -216

• -148

• -146

• -150

What is the sum of the first 50 terms of the series 2 + 17 + 32 + 47 + ...?

• 1,600

• 18,235

• 18,475

• 19,125

• Arithmetic

• Geometric

Answer explanation

Percentages are almost always Geometric.

• 315

• 330

• 345

• 360

Find the indicated nth partial sum of the arithmetic sequence. –3.1, –0.5, 2.1, 4.7, ..., n = 15

• -286.5

• 265.5

• 226.5

• 232.2

The sum of this arithmetic series is 595. a₁=28, and a_n=91. How many terms are there (what is n)?

• 9

• 10

• 11

• 12

Find the 22nd term of the following sequence:
5, 8, 11, ...

• 14

• 68

• 63

• 71

• 61
  

• 67
  

• 69

• 76