Chapter 11 - Sequences; Induction; the Binomial Theorem - Section 11.3 Geometric Sequences; Geometric Series - 11.3 Assess Your Understanding - Page 844: 23

The $n^{th}$ term of the sequence is given by the formula: $a_n =0 \ (\dfrac{1}{2})^{n-1}=0$ and $a_5=0 $

We are given: $a_{1}=0 ; \ r=\dfrac{1}{2}$ The $n^{th}$ term of the sequence is given by the formula: $a_n=a_1r^{n-1}$ $a_n =0 \ (\dfrac{1}{2})^{n-1}=0$ Now, the 5th term can be computed by substituting $5$ for $n$: $a_5=0 \ (\dfrac{1}{2})^{n-1}=0$