## College Algebra 7th Edition

RECALL: (1) The sum of an infinite geometric series is convergent if $|r| < 1$. The sum is given by the formula: $S_{\infty}=\dfrac{a}{1-r}$ (2) An infinite geometric series is divergent if $|r|\ge1$. (3) The common ratio $r$ of a geometric series can be found by dividing any term by the term before it: $r = \dfrac{a_n}{a_{n-1}}$ Solve for $r$ to obtain: $\require{cancel} r = \dfrac{-3(1.1)}{3} \\r = \dfrac{-\cancel{3}(1.1)}{\cancel{3}} \\r=-1.1$ Since $|-1.1|\ge1$, then the series is divergent.