Question

SOLVE.show your solution

1,find the sum of the first 18 terms of the arithmetic sequence whose general term is given by the equation an=4n-3.

2.what is the 15th term of geometric equence 3,6,12,24,...?

Answer 1

Step-by-step explanation:

1. 1 , 5 , 9 , ....

=> a = 1 and d = 4

=> S = 18/2 ( 2 + 17 × 4) = 630

2. a = 3 , r = 2

=> 15 the term = 3 × 2^14 = 49152