Provide an Appropriate Response $\sum _ { n = 1 } ^ { \infty } \frac { n } { 6 ^ { n - 1 } }$

question 175

Multiple Choice

Provide an appropriate response.
-Find the sum of the series $\sum _ { n = 1 } ^ { \infty } \frac { n } { 6 ^ { n - 1 } }$ by expressing $\frac { 1 } { 1 - x }$ as a geometric series, differentiating both sides of the resulting equation with respect to $x$ , and replacing $x$ by $\frac { 1 } { 6 }$ .

• A) \(\frac { 36 } { 49 }\)
• B) \(\frac { 36 } { 25 }\)
• C) \(\frac { 25 } { 36 }\)
• D) \(\frac { 49 } { 36 }\)