Sequence – a function whose domain is positive integers. Section 9.1 – Sequences.
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Transcript of Sequence – a function whose domain is positive integers. Section 9.1 – Sequences.
Sequence – a function whose domain is positive integers.
Sequence Notation
𝑓 (𝑥 )=2𝑥+1
𝑓 (𝑥 ) ,𝑔 (𝑥 ) , h(𝑥 ) 𝑎𝑛 ,𝑏𝑖 ,𝑐𝑘
𝑔 (𝑥 )=𝑥2−3 𝑥+7
h (𝑥 )= 𝑥+6
𝑥2+2 𝑥+3
𝑎𝑛=2𝑛+1
𝑏𝑖=𝑖2−3 𝑖+7
𝑐𝑘=𝑘+6
𝑘2+2𝑘+3
Section 9.1 – Sequences
Examples𝑾𝒓𝒊𝒕𝒆𝒕𝒉𝒆 𝒇𝒊𝒓𝒔𝒕 𝒇𝒐𝒖𝒓 𝒕𝒆𝒓𝒎𝒔 𝒇𝒐𝒓 {𝒂𝒌 }=𝒂𝒌=𝟐𝒌 .
2 (1 ) ,2 (2 ) ,2 (3 ) ,2(4)
2 ,4 ,6 ,8
Sequence Notation
𝑾𝒓𝒊𝒕𝒆𝒕𝒉𝒆 𝒇𝒊𝒓𝒔𝒕𝒕𝒉𝒓𝒆𝒆𝒕𝒆𝒓𝒎𝒔 𝒇𝒐𝒓 {𝒃𝒊 }=𝒃𝒊=𝒊𝟐
(𝟏 )𝟐 , (𝟐 )𝟐 , (𝟑 )𝟐
Section 9.1 – Sequences
𝟏 ,𝟒 ,𝟗
Sigma Notation – A mathematical notation that represents the sum of many terms using a formula.
Section 9.1 – Sequences
Examples
∑𝒏=𝟏
𝟒
𝟐𝒏
2 (1 )+2 (2 )+2 (3 )+2(4)
2+4+6+8
2+2+2+2+2+2
12
Sigma Notation
20
∑𝒌=𝟏
𝟔
𝟐
∑𝒊=𝟏
𝟑
(𝒊¿¿𝟐)¿
)
𝟏+𝟒+𝟗𝟏𝟒
Section 9.1 – Sequences
Express the sums in sigma notation.
∑𝒊=𝟏
𝟗𝟖
𝒊
1+2+3+4+…+98
1+12+
13+
14+…+
170
Sigma Notation
∑𝒌=𝟏
𝟕𝟎 𝟏𝒌
1−2+3−4+…−98
∑𝒊=𝟏
𝟗𝟖
(−𝟏)𝒊+𝟏𝒊
1−14+
19−
116
+…−149
∑𝒊=𝟏
𝟕
(−𝟏)𝒊+𝟏 𝟏𝒊𝟐
Section 9.1 – Sequences
Linearity of Sigma
∑𝒊=𝟏
𝒏
𝒄 𝒂𝒊=𝒄∑𝒊=𝟏
𝒏
𝒂𝒊
Sigma Notation
∑𝒌=𝟏
𝒏
(𝟑𝒌𝟐+𝟐𝒌−𝟕)
∑𝒊=𝟏
𝒏
(𝒂𝒊±𝒃𝒊)=¿∑𝒊=𝟏
𝒏
𝒂𝒊±∑𝒊=𝟏
𝒏
𝒃𝒊 ¿
∑𝒌=𝟏
𝒏
𝟑𝒌𝟐+∑𝒌=𝟏
𝒏
𝟐𝒌−∑𝒌=𝟏
𝒏
𝟕
Example
𝟑∑𝒌=𝟏
𝒏
𝒌𝟐+𝟐∑𝒌=𝟏
𝒏
𝒌−∑𝒌=𝟏
𝒏
𝟕→
Section 9.1 – Sequences
∑𝒌=𝟏
𝒏
𝒄=𝒏 ∙𝒄
Summation Rules
∑𝒌=𝟏
𝒏
𝒌𝟐=𝒏(𝒏+𝟏)(𝟐𝒏+𝟏)
𝟔
∑𝒌=𝟏
𝒏
𝒌=𝒏(𝒏+𝟏)
𝟐
∑𝒌=𝟏
𝒏
𝒌𝟑=¿(𝒏(𝒏+𝟏)𝟐 )
𝟐
¿
Section 9.1 – Sequences
∑𝒌=𝟏
𝟓𝟏
𝟒=¿¿
Summation Rules Examples
∑𝒌=𝟏
𝟏𝟓
𝒌𝟐=¿¿
∑𝒌=𝟏
𝟑𝟐
𝒌=¿¿
∑𝒌=𝟏
𝟗
𝒌𝟑=¿¿
𝟓𝟏 ∙𝟒=¿𝟐𝟎𝟒
𝟑𝟐(𝟑𝟐+𝟏)𝟐
=¿𝟓𝟐𝟖
𝟏𝟓(𝟏𝟓+𝟏)(𝟐 ∙𝟏𝟓+𝟏)𝟔
=¿𝟏𝟐𝟒𝟎
(𝟗(𝟗+𝟏)𝟐 )
𝟐
=¿𝟐𝟎𝟐𝟓
𝒔𝒖𝒎(𝒔𝒆𝒒 (𝟒 , 𝒙 ,𝟏 ,𝟓𝟒 ,𝟏 ))
𝒔𝒖𝒎(𝒔𝒆𝒒 (𝒙 ,𝒙 ,𝟏 ,𝟑𝟐 ,𝟏 ))
𝒔𝒖𝒎(𝒔𝒆𝒒 ( 𝒙𝟐 ,𝒙 ,𝟏 ,𝟏𝟓 ,𝟏))
𝒔𝒖𝒎(𝒔𝒆𝒒 ( 𝒙𝟑 ,𝒙 ,𝟏 ,𝟗 ,𝟏))
Section 9.1 – Sequences
∑𝒌=𝟏
𝟏𝟓
𝟒𝒌𝟐−𝟖𝒌+𝟔
Summation Rules Examples
𝟖∑𝒌=𝟏
𝟏𝟓
𝒌+¿¿
𝟏𝟓 ∙𝟔=¿
𝟗𝟎=¿
𝟖(𝟏𝟓 (𝟏𝟓+𝟏)𝟐 )+¿
𝟗𝟔𝟎+¿
𝟒 (𝟏𝟓 (𝟏𝟓+𝟏)(𝟐∙𝟏𝟓+𝟏)𝟔 )−𝟒𝟗𝟔𝟎−
𝒔𝒖𝒎 (𝒔𝒆𝒒 (𝟒 𝒙𝟐−𝟖 𝒙+𝟔 , 𝒙 ,𝟏 ,𝟏𝟓 ,𝟏))=¿
Section 9.1 – Sequences
𝟒∑𝒌=𝟏
𝟏𝟓
𝒌𝟐− ∑𝒌=𝟏
𝟏𝟓
𝟔
𝟒𝟎𝟗𝟎
𝟒𝟎𝟗𝟎