For each of the following geometric sequences, fill in the missing two terms and identify the common ratio, a r. Remember, you can always find r by dividing two consecutive terms such as 2 . a 1 (a) 2, 10, 50, , r  (c) 40, 20, 10, , r  (e) 5,  , 5, , 5 (f) 8, 20, 50, , r  r  2. One of the following sequences is arithmetic and one is geometric. Explain which is which. Sequence #1: 5, 15, 45, 135, 405 Sequence #2: 5, 15, 25, 35, 45 3. In a geometric sequence the first term is 5 and the second term is 20, which of the following is the fifth term? (1) 65 (3) 80 (2) 1,280 (4) 5,120 COMMON CORE ALGEBRA I, UNIT #6 – EXPONENTS, EXPONENTS, EXPONENTS – LESSON #9 eMATHINSTRUCTION, RED HOOK, NY 12571, © 2013 (b) 4, 8  , 16, , r  (d) 81, 54, 36, , r 