CHAPTER SEQUENCES AND SERIES OUTLINE Day Sectio Topic.7 Geometric Sequeces.8 Geometric Series 3.9 Ifiite Geometric Series ad Sigma Notatio 4 Review 5 Review 6 Chapter Test Terry Fox Math 007
.7 GEOMETRIC SEQUENCES Today we will review geometric sequece from grade 0 math. We will ow be able to solve for the umber terms i a sequece by usig logarithms. The parts of a geometric sequece: Example: 3, 6,, 4, 48, 96, 9, 384 The first term, 3 is called a or T. The secod term, 6 is called T. The umber of terms i the sequeces, 8 is called. Ay term divided by its precedig term is called the commo ratio, r. I this example, r is. The equatio represetig the value of ay term is: T ar. Workig with T ar : Give the sequece, 6, 8, 54,., determie the value of T 9. Terry Fox Math 007
Give the sequece 00 000, 80 000, 64 000, 3 768, what is the term umber of 3 768? Give T ad T 0 39366, determie the value of the commo ratio. I a geometric sequece, determie the sigle geometric mea betwee 4 ad 96. Terry Fox Math 007 3
A ball is dropped from a height of 8 meters. It rises to 70% of its previous height after each bouce. What is the maximum height that the ball will reach after it has bouced five times? Assigmet:.7 page 5 #-7, 9, 0 Terry Fox Math 007 4
.8 GEOMETRIC SERIES Last day we worked with geometric sequeces. Today we will work with geometric series. A series is the sum of geometric sequece. Example: 3, 6,, 4, 48, 96, 9 this is a geometric sequece 3+6++4+48+96+9 this is a geometric series Termiology for the series above: a T S 3 T 6 S 3 6 9 r Determiig the Sum of a Geometric Series: Give the series: +6+8+54+6 We will call S the sum of the series, therefore: If we multiply this by 3 (The commo ratio) we get: Terry Fox Math 007 5
This works for ay geometric series. From this kowledge we ca develop a formula. S a ar ar ar 3 ar 4... ar rs ar ar ar 3 ar 4... ar ar a r S is the formula for the sum of ay geometric series. r This formula is give o the provicial exam formula sheet. a rl Aother useful formula is S where l represets the last r term. This is also o the provicial exam formula sheet. Terry Fox Math 007 6
Applyig the formulae:. Determie the sum of the first 8 terms of the series: 8 3.. Determie the sum of the series: 64 3 6... 8 Terry Fox Math 007 7
3. The first term of a geometric series is 3 ad the sum of the series is 533. How may terms are i the series if the commo ratio is? 4. The sum of a geometric series is 78 ad the commo ratio is 5. What is T if there are six terms i the series? Terry Fox Math 007 8
5. For a give series, 3 3 S, determie T 3. 6. A patiet is prescribed a medicie for a ifectio. She must take 5mg o the first day ad take half of the previous days dosage for ie days. How much medicie has she take by the ed of her treatmet? Terry Fox Math 007 9
7. A ball is dropped from a height of 6 meters ad bouces back to a height of 75% of the previous height? What is the total vertical distace that the ball has traveled after the 5 th bouce? Assigmet:.8 page 4 #-0, 3, 4 Terry Fox Math 007 0
.9 INFINITE GEOMETRIC SERIES Today we will lear how to fid the sum of ifiite geometric series ad lear how to work with series writte i sigma otatio. Sigma otatio is a shorthad expressio for a series. Fidig the sum of a ifiite series: Notice the patter of the followig series S 3 4 S 4. 4 8 S 5 4 8 6 Notice that with a commo ratio of, the more that we multiply by the commo ratio by itself, the closer it gets to be equal to zero. From the formula S a r r Terry Fox Math 007
Therefore: For ay ifiite series with a commo ratio 0 r we ca have a fiite sum ad the formula a that we ca use is: S r If the absolute value of r does ot fit the restrictio, the we caot determie a sum. Applicatios:. Determie the sum of the series: 3 6 3 Terry Fox Math 007
. A ifiite geometric series has a fiite sum. If the commo ratio is x, what are the possible values for x? 3. The first term of a ifiite geometric series is 0 ad the sum to ifiity is 30. What is the commo ratio? Terry Fox Math 007 3
3 4. The sum to ifiity of a series is ad the commo ratio is. 5 4 What is the first term? Sigma Notatio: Sigma otatio is shorthad for the sum of. Give: 5 3 we ca expad this series by subbig the values of startig at ad cotiuig util it becomes 5. 3 3 4 3 3 3 5 which becomes 6 4 48 Notice that there were 4 terms. We ca always determie the umber of terms i the series by subtractig the bottom umber from the top. 5 4 Terry Fox Math 007 4
Also otice that the commo ratio is. It ca be determied by lookig at the power or by dividig term by term. If you are ever i doubt about the commo ratio, it ca be determied this way. Determiig the sum: 0 4 5 3 k 3 k Terry Fox Math 007 5
Try these:. Determie the umber of terms i 34 8 5 5 k 3. Determie the first term ad the commo ratio i 4 k 3. Determie the sum for 3 Terry Fox Math 007 6
4. Determie the sum for k k 5. Determie the sum for log 4 Terry Fox Math 007 7
6. A ball is dropped from a height of 6 meters ad bouces back to a height of 75% of the previous height? What is the total vertical distace that the ball has traveled after the ball has come to rest? Assigmet:.9 page 30 ad Sigma Worksheet #-6 (.9) ad all from the worksheet Terry Fox Math 007 8