a. −3, 9,−27, 81,−243,···
Ans: an = (−3)n 11111
b. 1, 2, 6, 24, 120, 720,··· Ans: an = 1
n! 23456
c. −3, 4,−5, 6,−7,··· Ans: an =(−1)nn+1
n+2 1111
d. 1, 2,3, 4,5, 6,7, 8,··· Ans: an = (n)(−1)n+1
1 9 25 49 81 121 e. 2, 16, 36, 64, 100, 144 ···
Ans: an = (2n − 1)2
