Mathematics 9709 · AS & A Level · Series

Series — practice question

A geometric progression has second term $-120$ and sum to infinity $160$.
(a)[4]

Find the value of the common ratio.

(b)[3]

The first nine terms of the progression are now removed. Find the sum to infinity of the terms that remain in the progression.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Form the equations $ar=-120$ and $\frac{a}{1-r}=160$.” …

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI