Question

QUESTION 7 (TOTAL: 14 MARKS) (a) The first three terms of a geometric series are (k+4), k, (2k - 15) respectively, where k is a positive constant. Find the sum to infinity of this series. (8 MARKS) (b

Answer 1

64

Explanation:

We have k² = (k + 4)(2k - 15) = 2k² - 7k - 60.

=> k² - 7k - 60 = 0, k = -5 (rej.) or k = 12.

We have r = k/(k + 4) = 3/4.

Thus, sum to infinity of the series = 16/(1 - 3/4) = 64.