254,953 views
6 votes
6 votes
Hey, i need help with this question. can anyone help me?

Hey, i need help with this question. can anyone help me?-example-1
User Alexander  Petryakov
by
2.6k points

2 Answers

19 votes
19 votes
The answer is 47 or the other answer connected to it is 23
User Jecki
by
2.5k points
13 votes
13 votes

SOLUTION

The given sequence is:


7,21,63,189,\cdots

The first term of the sequence is 7.

Notice that the sequence has a common ratio of:


r=(21)/(7)=(63)/(21)=\cdots=3

The recursive formula of a geometric series is:


a_n=a_(n-1)(r)

Substituting r=3 gives:


a_n=3a_(n-1)

User Silver Ringvee
by
3.0k points