Consider the series (7,-14,28,-56, ) whose (n )th term is obtained by multiplying the…
MATHEMATICS · Multi-part · CBSE · Mathematics · Sequences and Series · Sequences and Series
Problem
Consider the series 7,−14,28,−56,… whose nth term is obtained by multiplying the preceding term by −2.
(i) Derive a general expression for the sum of the first n terms.
(ii) Using the expression obtained in part (i), evaluate the sum of the first 10 terms.
(iii) Determine, with justification, whether the sum of the first 15 terms is positive or negative.