Question

use general term to find the 13th term from the series 1/2:1/4:1:8:1/16

Answer 1

Answer:

$a = \frac{1}{2 }\\ a2 = \frac{1}{4} \\ d = a2 - a \\ d = \frac{1}{4}- \frac{1}{2}$

$d = \frac{2 - 4}{8} \\d = \frac{ - 2}{8} \\ d = \frac{ - 1}{4}$

$a13 = a + (n - 1)d \\ a13 = \frac{1}{2} + (12) \frac{ - 1}{4} \\ a13 = \frac{1}{2} + ( - 3)$

$a13 = \frac{1}{2} - 3 \\ a13 = \frac{1 - 6}{2} \\ a13 = \frac{ - 5}{2}$