## Core 2 – Geometric Sequences

This final post on this topic will look at geometrical sequences. Again you need to know how to use the formulae in the formula book. One difference to arithmetic sequences is that you also have an infinite sum formula. This can be used when the common ratio r is between but not including -1 and 1.

Geometric questions can be combined with logs so come back to this topic again when you’ve had time to look at logs. As always if you need more help then just ask at our Facebook Support Group (link on the right)

June 2007 Question 2 – answer here

June 2010 Question 5 – answer here

If you are stuck then try this video for help

## Core 2 – recurrence relationship

Sequences can also be written as recurrence relationships. Some of these are arithmetic and geometric but some are neither. The video below explains recurrence relationships and how they work. Once you are happy with it then try the exam questions.

January 2006 Question 5 – answer here

June 2013 Question 7 – answer here

## Core 2 – Sigma notation

Yesterday you looked at the basics of arithmetic sequences. Today we look at how these sequences can be written using sigma notation. The video below shows what sigma notation is and the exam questions below will be good practice.

Now try these exam questions. Any questions then just ask on our Facebook support group.

January 2010 Question 4 – answer here

June 2014 Question 8 – answer here