Lesson Summary: By the end of this lesson, one should be familiar with r- the common ration of a geometric sequence which can be found by dividing the previous term from the current term which should equal a constant (u sub n / u sub n-1 = r). Furthermore, one should know that the explicit formula of a geometric sequence is exponential. In addition, one should be familiar with finding the sums of a geometric series using one of the sigma notations including sum to infinitu