Chapter 12 - Sequences; Induction; the Binomial Theorem - 12.3 Geometric Sequences; Geometric Series - 12.3 Assess Your Understanding - Page 824: 8

True

For a geometric sequence with first term $a_1$ and common ratio $r$, where $r\not=0,r\not=1$, the sum of the first $n$ terms is $S_n=a_1\cdot\dfrac{1-r^n}{1-r}$. The statement is TRUE as it represents the formula of computing the sum of the first $n$ terms of a geometric sequence.