Arithmetic and Geometric Sequences

Which of the following is an arithmetic sequence?

• {1, 2, -3, -4, 10}
• {-2, -6, -10, -14, -18}
• {1, 2, 4, 8, 16}
• {100, -100, 200, -200}

Which of the following is a geometric sequence?

• {3, -9, 27, -81, 243}
• {3, 6, 9, 12, 15}
• {3, 2, 1, 0, -1}
• {1, 4, 9, 16, 25, 36}

An arithmetic sequence is below. What is the missing term?
{3, 5, 7, __, 11, 12}

• 8
• 9
• 10
• 11

A geometric sequence is below. What is the missing term?
{-1, -3, -9,  __, -81}

• -18
• -27
• -243
• -781