12345
of 5

Geometric Sequences

 

term: a1 , term value: 3 ... term: a2 , term value: 3( -2 )^( 1 ) = -6 ... term: a3 , term value: 3( -2 )^( 2 ) = 12 ... term: a4 , term value: 3( -2 )^( 3 ) = -24 ... term: a5 , term value: 3( -2 )^( 4 ) = 48

See the pattern?

Check out the term number and the guy that's changing on the right:

                                  term: a1 , term value: 3( -2 )^( 0 ) ... term: a2 , term value: 3( -2 )^( 1 ) ... term: a3 , term value: 3( -2 )^( 2 ) ... term: a4 , term value: 3( -2 )^( 3 ) ... term: a5 , term value: 3( -2 )^( 4 ) ... term: a50 , term value: 3( -2 )^( 49 )
                                                            Let's just leave it like
                                                            this -- it's a really huge
                                                            number!

So, what's the formula for the nth term?

an = 3( -2 )^( n - 1 )