Question 1188227


the following sequence:

(1) {{{3}}}, {{{5}}}, {{{8}}}, ...


This sequence is not arithmetic ({{{no}}} common difference {{{d}}}), and it's not geometric ( no common ratio {{{r}}}) .

answer: {{{neither}}}


(2) {{{2a}}}, {{{4a^2}}}, {{{8a^3}}}, ...

not arithmetic (no common difference {{{d}}} )
 
let's check common ratio: 

{{{r=4a^2/2a=2a}}}
{{{r=8a^3/4a^2=2a}}}

The {{{ratio}}} between the consecutive terms is {{{constant}}} so we can conclude that the sequence is {{{geometric}}}.