The sum to infinity of a geometric progression is −110 − 1 10 and the first term is −18 − 1 8 . Find the common ratio of the progression.

Question 1 Report

The sum to infinity of a geometric progression is $- \frac{1}{10}$ and the first term is $- \frac{1}{8}$ . Find the common ratio of the progression.

- \frac{1}{4}

- \frac{1}{4}

- \frac{1}{4}

- \frac{1}{2}

Answer Details

Sr = $\frac{a}{1 - r}$
$- \frac{1}{10}$ = $\frac{1}{8} \times \frac{1}{1 - r}$
$- \frac{1}{10}$ = $\frac{1}{8 (1 - r)}$
$- \frac{1}{10}$ = $\frac{1}{8 - 8 r}$
cross multiply...
-1(8 - 8r) = -10
-8 + 8r = -10
8r = -2
r = -1/4

Read lesson note on Sets (WAEC)

Read lesson note on Sequence And Series (WAEC)

Sets

Sequence And Series

View Answer

Download The App On Google Playstore

Everything you need to excel in JAMB, WAEC & NECO

Personalized AI Learning Chat Assistant

Thousands of JAMB, WAEC & NECO Past Questions

Over 1200 Lesson Notes

Offline Support - Learn Anytime, Anywhere

Green Bridge Timetable

Literature Summaries & Potential Questions

Track Your Performance & Progress

In-depth Explanations for Comprehensive Learning