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Arithmetic and Geometric Sequences and their Summation. 14.1 Sequences. arithmetic sequence. geometric sequence. geometric sequence. geometric sequence. Find the next two terms of the following sequences : 2, 5, 8, 11,…… 2, 6, 18, 54, …. 2, 4, 8, 16,……. 5, -25, 125, -625, ….
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14.1 Sequences arithmetic sequence geometric sequence geometric sequence geometric sequence Find the next two terms of the following sequences : 2, 5, 8, 11,…… 2, 6, 18, 54, …. 2, 4, 8, 16,……. 5, -25, 125, -625, …. 3, 4, 6, 9, 13, ……. 5, 2, -1, -4, ….. 0, sin20o, 2sin30o, 3sin40o arithmetic sequence
14.1 Sequences Consider the following sequence:1, 3, 5, 7, 9, ….., 111 3 is the second term of the sequence, mathematically, T(2) = 3 or T2 = 3 1 is the first term of the sequence,mathematically, T(1) = 1 or T1 = 1 5 is the third term of the sequence, mathematically, T(3) = 5 or T3 = 5 111 is the nth term of the sequence, mathematically, T(n) = 111 or Tn = 111
14.1 Sequences Consider the sequence 2, 4, 8, 16, …. So, the sequence can be represented by the general term T(n) = 2n or Tn = 2n The sequence is formed from timing 2 to the previous term.
14.2 Arithmetic Sequence An arithmetic sequence(A.S. /A.P.) is a sequence having a common difference.
14.2 Arithmetic Sequence Illustrative Examples
14.2 Arithmetic Sequence Arithmetic Means When a, b and c are three consecutive terms of arithmetic sequence, the middle term b is called the arithmetic mean of a and c.
14.2 Arithmetic Sequence Arithmetic Means Insert two arithmetic means between 11 and 35.
14.2 Arithmetic Sequence Insert two arithmetic means between 11 and 35.
14.3 Geometric Sequence A geometric sequence(G.S. / G.P.) is a sequence having a common ratio.
14.3 Geometric Sequence Illustrative Examples
14.3 Geometric Sequence Geometric Means When x, y and z are three consecutive terms of geometric sequence, the middle term y is called the geometric mean of x and z.
14.3 Geometric Sequence Geometric Means Insert two geometric means between 16 and -54.
14.3 Geometric Sequence Insert two geometric means between 16 and -54.
14.4 Series The expression T(1) + T(2) + T(3) +….+ T(n) is called a series. We usually denote the sum of the first n term of a series by the notation S(n). Let’s consider a sequence : T(1), T(2), T(3), T(4), …., T(n)
14.5 Arithmetic Series Arithmetic Sequence : 2, 5, 8, 11, … Arithmetic Series : 2 + 5 + 8 + 11 + ….
14.5 Arithmetic Series Formula of Arithmetic Series S(n) = a + a + d + a + 2d + a + 3d + …. + a + (n - 1)d l
14.5 Arithmetic Series Formula of Arithmetic Series S(n) = l + l - d + l - 2d + l - 3d + …. + a + d+ a
14.5 Arithmetic Series S(n) = a + a + d + a + 2d + a + 3d + ………... + a + (n - 1)d S(n) = l + l – d + l - 2d + l - 3d + ….+ a + d+ a 2S(n) =(a + l)+(a + l)+(a + l)+(a + l)+….. +(a + l) 2S(n) = n(a + l)
14.6 Geometric Series Geometric Sequence : 3, 9, 27, 81, … Geometric Series : 3 + 9 + 27 + 81
14.6 Geometric Series Formula of Geometric Series S(n) = a + aR + aR2 +aR3+ …. + aRn-1
14.6 Geometric Series Formula of Geometric Series R.S(n) = aR + aR2 + aR3 +aR4+ …. + aRn
Subtracting two series S(n) = a + aR + aR2 +aR3+ …. + aRn-1 S(n) –R.S(n) = a - aRn R.S(n) = aR + aR2 + aR3 +aR4+ …. + aRn (1 – R) S(n) = a (1 – Rn)
14.6 Geometric Series Timing –1 on both numerator and denominator
14.6 Geometric Series Sum to Infinity of a Geometric Series
14.6 Geometric Series Sum to Infinity of a Geometric Series Consider such a Geometric Series What is the value of common ratio R ?
14.6 Geometric Series Sum to Infinity of a Geometric Series Consider Rn where n tends to the infinity
What will occur for if n tends to infinity ? where –1< R <1
(extension module) Summation Notation
Consider the symbol where T( r ) = 3r + 5 = 3(1) + 5 + 3(2) + 5+3(3) + 5 + 3(4) +5 = 50