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11.2: Arithmetic Sequences & Series. n th Term of an Arithmetic Sequence: a n = a 1 + ( n – 1) d Ex. 1 Determine the following using the table below. n th Term of an Arithmetic Sequence: a n = a 1 + ( n – 1) d Ex. 1 Determine the following using the table below.
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nth Term of an Arithmetic Sequence: an = a1 + (n – 1)d Ex. 1Determine the following using the table below.
nth Term of an Arithmetic Sequence: an = a1 + (n – 1)d Ex. 1Determine the following using the table below. a) Find the 10th term in the sequence.
nth Term of an Arithmetic Sequence: an = a1 + (n – 1)d Ex. 1Determine the following using the table below. a) Find the 10th term in the sequence. an = a1 + (n – 1)d
nth Term of an Arithmetic Sequence: an = a1 + (n – 1)d Ex. 1Determine the following using the table below. a) Find the 10th term in the sequence. an = a1 + (n – 1)d a10 = a1 + (10 – 1)d
nth Term of an Arithmetic Sequence: an = a1 + (n – 1)d Ex. 1Determine the following using the table below. a) Find the 10th term in the sequence. an = a1 + (n – 1)d a10 = 55 + (10 – 1)d
nth Term of an Arithmetic Sequence: an = a1 + (n – 1)d Ex. 1Determine the following using the table below. a) Find the 10th term in the sequence. an = a1 + (n – 1)d a10 = 55 + (10 – 1)(-6)
nth Term of an Arithmetic Sequence: an = a1 + (n – 1)d Ex. 1Determine the following using the table below. a) Find the 10th term in the sequence. an = a1 + (n – 1)d a10 = 55 + (10 – 1)(-6)
nth Term of an Arithmetic Sequence: an = a1 + (n – 1)d Ex. 1Determine the following using the table below. a) Find the 10th term in the sequence. an = a1 + (n – 1)d a10 = 55 + (10 – 1)(-6) a10 = 55 + (9)(-6)
nth Term of an Arithmetic Sequence: an = a1 + (n – 1)d Ex. 1Determine the following using the table below. a) Find the 10th term in the sequence. an = a1 + (n – 1)d a10 = 55 + (10 – 1)(-6) a10 = 55 + (9)(-6) a10 = 55 – 54
nth Term of an Arithmetic Sequence: an = a1 + (n – 1)d Ex. 1Determine the following using the table below. a) Find the 10th term in the sequence. an = a1 + (n – 1)d a10 = 55 + (10 – 1)(-6) a10 = 55 + (9)(-6) a10 = 55 – 54 a10 = 1
b) Write an equation for the nth term of the sequence. an = a1 + (n – 1)d
b) Write an equation for the nth term of the sequence. an = a1 + (n – 1)d an = 55 + (n – 1)(-6)
b) Write an equation for the nth term of the sequence. an = a1 + (n – 1)d an = 55 + (n – 1)(-6) an = 55 - 6(n – 1)
b) Write an equation for the nth term of the sequence. an = a1 + (n – 1)d an = 55 + (n – 1)(-6) an = 55 - 6(n – 1) an = 55 - 6n + 6
b) Write an equation for the nth term of the sequence. an = a1 + (n – 1)d an = 55 + (n – 1)(-6) an = 55 - 6(n – 1) an = 55 - 6n + 6 an = - 6n + 61
b) Write an equation for the nth term of the sequence. an = a1 + (n – 1)d an = 55 + (n – 1)(-6) an = 55 - 6(n – 1) an = 55 - 6n + 6 an = - 6n + 61
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 ***Find the missing terms in the sequence!
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 a1a2a3a4a5a6
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 a1a2a3a4a5a6
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 a1a2a3a4a5a6 n = 6 a1 = 24 a6 = -1
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 a1a2a3a4a5a6 n = 6 a1 = 24 a6 = -1 an = a1 + (n – 1)d
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 a1a2a3a4a5a6 n = 6 a1 = 24 a6 = -1 an = a1 + (n – 1)d -1 = 24+ (6 – 1)d
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 a1a2a3a4a5a6 n = 6 a1 = 24 a6 = -1 an = a1 + (n – 1)d -1 = 24+ (6 – 1)d -1 = 24 + 5d -25 = 5d -5 = d
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 a1a2a3a4a5a6 n = 6 a1 = 24 a6 = -1 an = a1 + (n – 1)d -1 = 24+ (6 – 1)d -5 = d a1 = 24
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 a1a2a3a4a5a6 n = 6 a1 = 24 a6 = -1 an = a1 + (n – 1)d -1 = 24+ (6 – 1)d -5 = d a1 = 24 a2 = 24 + (-5) = 19
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 a1a2a3a4a5a6 n = 6 a1 = 24 a6 = -1 an = a1 + (n – 1)d -1 = 24+ (6 – 1)d -5 = d a1 = 24 a2 = 24 + (-5) = 19 a3 = 19 + (-5) = 14
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 a1a2a3a4a5a6 n = 6 a1 = 24 a6 = -1 d = -5 a1 = 24 a2 = 24 + (-5) = 19 a3 = 19 + (-5) = 14 a4 = 14 + (-5) = 9
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 a1a2a3a4a5a6 n = 6 a1 = 24 a6 = -1 d = -5 a1 = 24 a2 = 24 + (-5) = 19 a3 = 19 + (-5) = 14 a4 = 14 + (-5) = 9 a5 = 9 + (-5) = 4
Ex. 2 Find the arithmetic means in the sequence below. 24, ___, ___, ___, ___, -1 a1a2a3a4a5a6 n = 6 a1 = 24 a6 = -1 d = -5 a1 = 24 a2 = 24 + (-5) = 19 a3 = 19 + (-5) = 14 a4 = 14 + (-5) = 9 a5 = 9 + (-5) = 4
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following:
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following: Sn = ½n[ 2a1 + (n – 1)d ]
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following: Sn = ½n[ 2a1 + (n – 1)d ] OR Sn = ½n[ a1 + an ]
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following: Sn = ½n[ 2a1 + (n – 1)d] OR Sn = ½n[ a1 + an ]
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following: Sn = ½n[ 2a1 + (n – 1)d ] OR Sn = ½n[ a1 + an ]
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following: Sn = ½n[ 2a1 + (n – 1)d ] OR Sn = ½n[ a1 + an ] Ex. 3 Find Snfor each of the following:
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following: Sn = ½n[ 2a1 + (n – 1)d ] OR Sn = ½n[ a1 + an ] Ex. 3 Find Snfor each of the following: a) a1= 58, an = -7, n = 26
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following: Sn = ½n[ 2a1 + (n – 1)d ] OR Sn = ½n[ a1 + an ] Ex. 3 Find Snfor each of the following: a) a1= 58, an = -7, n = 26
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following: Sn = ½n[ 2a1 + (n – 1)d ] OR Sn = ½n[ a1 + an ] Ex. 3 Find Snfor each of the following: a) a1= 58, an = -7, n = 26 Sn = ½n[ a1 + an ]
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following: Sn = ½n[ 2a1 + (n – 1)d ] OR Sn = ½n[ a1 + an ] Ex. 3 Find Snfor each of the following: a) a1= 58, an = -7, n = 26 Sn = ½n[ a1 + an ] Sn = ½(26)[ 58- 7 ]
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following: Sn = ½n[ 2a1 + (n – 1)d ] OR Sn = ½n[ a1 + an ] Ex. 3 Find Snfor each of the following: a) a1= 58, an = -7, n = 26 Sn = ½n[ a1 + an ] Sn = ½(26)[ 58 - 7 ] Sn = ½(26)[ 51 ]
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following: Sn = ½n[ 2a1 + (n – 1)d ] OR Sn = ½n[ a1 + an ] Ex. 3 Find Snfor each of the following: a) a1= 58, an = -7, n = 26 Sn = ½n[ a1 + an ] Sn = ½(26)[ 58 - 7 ] Sn = ½(26)[ 51 ] Sn = 13[ 51 ]
Sum of an Arithmetic Series The sum Snof the first n terms of an arithmetic series is given by the following: Sn = ½n[ 2a1 + (n – 1)d ] OR Sn = ½n[ a1 + an ] Ex. 3 Find Snfor each of the following: a) a1= 58, an = -7, n = 26 Sn = ½n[ a1 + an ] Sn = ½(26)[ 58 - 7 ] Sn = ½(26)[ 51 ] Sn = 13(51) = 663
Ex. 416 ∑ (4k – 2) k = 1
Ex. 416 ∑ (4k – 2) k = 1 n = 16
Ex. 416 ∑ (4k – 2) k = 1 n = 16 a1= 4(1) – 2 = 2
Ex. 416 ∑ (4k – 2) k = 1 n = 16 a1= 4(1) – 2 = 2 an= 4(16) – 2 = 62