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Learn how to find numbers in arithmetic sequences using recursive and explicit formulas. Understand the concept of common difference and its relationship with slope. Practice solving arithmetic sequence problems.
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Week 5 Warm Up 09.12.11 { -3, 8, 19, 30, 41, . . } n = 3 1) tn = 2) tn - 1= 3) t6 =
a = { 4, 7, 10, 13, 16, . . .} Re 1 then a3 - 1= if a3 = 10 7 d = 3 Recursive Formula: Arithmetic an= an - 1+ 3 a50 = a49+ 3
Explicit Formula You Do not need to know the previous number to find a number in the sequence. an = dn + a0 Ex 1
Ex 2 • • • •
Ex 2 • output: 4, 7, 10, 13, • • • input: 1, 2, 3, 4 common difference? goes up by 3 common difference = slope
• • • • • y = mx + b Ex 3 y = x + 3 1 Explicit Formula an = 3n + 1
• • • • • • an = 3n + 1 an = 3n + 1 Ex 4 a3 = 3(3) + 1 a50 = 3(50) + 1 a3 = 9 + 1 a50 = 150 + 1 a3 = 10 a50 = 151
a = { 10, 8, 6, 4, 2,. . .} Ex 5 y = -2x + 12 12 tn = -2n + 12 10 t0 = -2(0) + 12 8 6 t0 = 12 4 t0 = y-intercept
Explicit Formula: Arithmetic Sequence an = dn + a0 -2, 7, 16, 25, . . . Ex 6 d = 9 a0 = -11 an = 9n - 11
Do: 1 What is the explicit formula? -6, 1, 8, 15, 22, . . . Assignment: Handouts – 1.3 Day 1 Explicit Formulas
a10 an = -2n + 12 a10 = -2( 10 ) + 12 a10 = -20 + 12 a10 = -8
• • • • • • an = 3n + 1 Ex 5 a0 = 3(0) + 1 a0 = 0 + 1 a0 is the y-intercept a0 = 1
Re 1 Recursive Formulas You have to know the previous number to find the next number. = tn tn– 1 + d Arithmetic Geometric tn = r ( ) tn-1