M3U1D3 Warm Up 12, 6, 0, -6, -12 12, 4, 4/3, 4/9, 4/27 2, 5, 8, 11, 14 0, 2, 6, 12, 20 Arithmetic a...
-
Upload
darrell-mccarthy -
Category
Documents
-
view
214 -
download
1
Transcript of M3U1D3 Warm Up 12, 6, 0, -6, -12 12, 4, 4/3, 4/9, 4/27 2, 5, 8, 11, 14 0, 2, 6, 12, 20 Arithmetic a...
M3U1D3 Warm Up
12, 6, 0, -6, -1212, 4, 4/3, 4/9, 4/27
2, 5, 8, 11, 140, 2, 6, 12, 20
Arithmetican = an-1 + 4
Geometrican = a1(1/2)n-1
Homework Check:
Homework Check:
M3U1D3 Arithmetic Series
Objective:To write arithmetic and geometric
sequences both recursively and with an explicit formula, use them to model situations, and translate between the
two forms. F-BF.2
How do I know if it is an arithmetic series?A series is the expression for the sum of
the terms of a sequence, not just “what are the next terms.”
Ex: 6, 9, 12, 15, 18 . . .
This is a list of the numbers in the pattern an not a sum. It is a sequence. Note it goes on forever, so we say it is an infinite sequence.
Ex: 6 + 9 + 12 + 15 + 18
Note: if the numbers go on forever, it is infinite; if it has a definitive ending it is finite.
Here we are adding the values. We call this a series. Because it does not go on forever, we say it is a finite series.
Evaluating a SeriesTo evaluate a series, simply add up the values!
Ex 1: 2, 11, 20, 29, 38, 47
2+11+20+29+38+47 = 147
Easy Cheesy! But isn’t there a quicker way to do this???
Sum of a Finite Arithmetic Series)(
21 nn aa
nS
)472(2
6nS
Where: Sn is the sum of all the terms
n = number of terms
a1 = first term
an = last termFrom our last example: 2+11+20+29+38+47 = 147
119)295(2
7nS
147
Let’s try one: evaluate the series:
5, 9, 13,17,21,25,29
Just like yesterday!!!
Vocabulary of Arithmetic Sequences and Series (Universal)
1a First term
na nth term
nS sum of n terms
n number of terms
d common difference
n 1
n 1 n
nth term of arithmetic sequence
sum of n terms of arithmetic sequen
a a n 1 d
nS a a
2ce
WRITE THESE FORMULAS DOWN ON YOUR HINTS CARD!!!
Example 2:Find the sum of the first 50 terms of an arithmetic series with a1 = 28 and d = -4
We need to know n, a1, and a50.
n= 50, a1 = 28, a50 = ?? We have to find it.
Example 2 CONT.
a50 = 28 + -4(50 - 1) = 28 + -4(49) = 28 + -196 = -168
So n = 50, a1 = 28, & a50 =-168
S50 = (50/2)(28 + -168) = 25(-140) = -3500
To write out a series and compute a sum can sometimes be very tedious. Mathematicians often use the Greek letter sigma & summation notation to simplify this task.
B
nn A
a
UPPER BOUND(NUMBER)
LOWER BOUND(NUMBER)
SIGMA(SUM OF TERMS) NTH TERM
(SEQUENCE)
SummationWhen we don’t want to write out a whole bunch of numbers in the series, the summation symbol is used when writing a series. The limits are the greatest and least values of n.
Summation symbol
Upper Limit (greatest value of n)
Lower Limit (least value of n)
Explicit function for the sequence
So, the way this works is plug in n=1 to the equation and continue through n=3.
(5*1 + 1) + (5*2 +1) + (5*3 + 1) = 33
Writing a series in summation formEx 3: 102 + 104 + 106 + 108 + 110 + 112
n = 6 terms
1st term = 102
Rule: Hmmmm. . . .
Rule = 100 + 2n
Let’s Evaluate: Yes, you can add manually. But let’s try using the shortcut:
)(2
1 nn aan
S 642)112102(2
6nS
Let’s try someFind the number of terms,
the first term and the last term. Then evaluate the series:
N = 10
1st = 1
Last = 10
a1= 1-3 = -2
a10 = 10-3 = 7
N = 4
1st = 2
Last = 5
4+9+16+25 = 54
Notice we can use the shortcut here:
Why is the answer not 58?
Note: this is NOT an arithmetic series. You can NOT use the shortcut; you have to manually crunch out all the values.25)5(5)72(
2
10nS
Why 4?
63Find S of 19, 13, 7,...
1a First term
na nth term
nS sum of n terms
n number of terms
d common difference
-19
63
??
x
6
n 1a a n 1 d
?? 19 6 1
?? 353
3 6
353
n 1 n
nS a a
2
63
633 3S
219 5
63 1 1S 052
To find an, substitute & Evaluate!!!
Ex 4:
Compound Interest REVISEDCompound interest formula:
A = the compound amount or future valueP = principali = interest rate per period of compounding
n=number of times compounded per yeart = number of yearsI = interest earned
PAIandniPA nt )/1(
ProjectDistribute Project
directions and rubric
DUE Sept. 15th !!!
Classwork:U1D3 Arithmetic Series and
Summation Notation WS #1-16
Homework:U1D3 WS2 #1-14
AND have your parent read the class
letter then sign & return the actual Math III acknowledgement
sheet to me.