Question

Find the tenth term in each sequence:- A. -2,-6,-18,-54 B. 7,9,12

Answer 1

Answer:  A) 39,366        B) 61

Step-by-step explanation:

A) -2, -6, -18, -54, ....

each following term is multiplied by 3 so it is a geometric series

$a_n=-2(3)^{n-1}\\\\\\a_{10}=-2(3)^{10-1}\\.\quad =-2(3)^{9}\\.\quad =-2(19,683)\\.\quad =\boxed{-39,366}$

B) 7, 9, 12, ...

each following term is +n, so it is neither arithmetic or geometric

7 + 2 = 9

9 + 3 = 12

12 + 4 = 16

16 + 5 = 21

21 + 6 = 27

27 + 7 = 34

34 + 8 = 42

42 + 9 = 51

51 + 10 = 61           The 10th term is 61

Answer 2

Tenth term in A is -39366 but B isn’t a sequence or series