Question

The first and last terms of a G.P. are $a$ and $l$ respectively; $r$ being its common ratio; then the number of terms in this G.P. is.

• A. $\frac { \log l - \log a } { \log r }$
• B. $1 - \frac { \log l - \log a } { \log r }$
• C. $\frac { \log a - \log l } { \log r }$
• D. $1 + \frac { \log l - \log a } { \log r }$

Answer 1

Answer: (D)

$1 + \frac { \log l - \log a } { \log r }$

Answer 2

$l = a r ^ { n - 1 }$ $\Rightarrow$ $\frac { l } { a } = r ^ { n - 1 }$ $\Rightarrow$.