3. Sequences and Series Learn what is meant by a geometric sequence Learn how to find the nth term of a geometric sequence

4. Paper folding If you fold a piece of paper in half 50 times, how thick would it be?? Lets assume it is 0.1mm thick to start with… 0.1 x 2 x 2 x 2 x 2 x 2….. Surely there is a quicker way!!! 0.1 x 2 50 = 113,000,000,000,000mm = 113,000,000km Don’t try this at home!!

5. Geometric Sequences In general… u n =u 1 x r n-1 1 st termCommon ratio From the formula booklet

6. Example 1 Find the 20 th term of the sequence 2, 6, 18, 54…. u n =u 1 x r n-1 u 1 = 2r = 3n = 20 u 20 =2 x 3 19 u 20 =2,324,522,934

7. Activity 6 questions

8. Activity http://www.mathsnetalevel.com/question.p hp?ref=188

9. Plenary http://www.mymaths.co.uk/indexLog.asp?h =7773 Pairs Game Converging Series Sum of n terms