Mathematics Grade 12 15 min

Partial sums mixed review

Partial sums mixed review

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1

Introduction & Learning Objectives

Learning Objectives Identify if a series is arithmetic, geometric, or telescoping. Calculate the nth partial sum (S_n) for arithmetic and geometric series. Derive a formula for the nth partial sum of a telescoping series. Determine if a series converges or diverges by finding the limit of its sequence of partial sums. Apply the formula for the sum of a convergent infinite geometric series. Use the nth-Term Test to identify divergent series. Can you add infinitely many numbers together and get a finite result? 🤯 This lesson explores the bridge between finite sums and the infinite! This tutorial is a mixed review of partial sums, the building blocks for understanding infinite series. We will revisit arithmetic, geometric, and telescoping series, focusing on how their partial...
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Key Concepts & Vocabulary

TermDefinitionExample SeriesThe sum of the terms in a sequence. An infinite series is denoted by Σ a_n from n=1 to ∞.The sequence 1, 1/2, 1/4, 1/8, ... corresponds to the series 1 + 1/2 + 1/4 + 1/8 + ... Partial Sum (S_n)The sum of the first 'n' terms of a series. The sequence of partial sums is {S_1, S_2, S_3, ...}.For the series 1 + 2 + 3 + 4 + ..., the third partial sum is S_3 = 1 + 2 + 3 = 6. Arithmetic SeriesA series in which the difference between consecutive terms (the common difference, 'd') is constant.2 + 5 + 8 + 11 + ... (Here, the common difference d = 3). Geometric SeriesA series in which the ratio between consecutive terms (the common ratio, 'r') is constant.3 + 6 + 12 + 24 + ... (Here, the common ratio r = 2). Telescoping SeriesA series where...
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Core Formulas

nth Partial Sum of an Arithmetic Series S_n = \frac{n}{2}(a_1 + a_n) = \frac{n}{2}(2a_1 + (n-1)d) Use this to find the sum of the first 'n' terms of an arithmetic series, where a_1 is the first term and 'd' is the common difference. nth Partial Sum of a Geometric Series S_n = a_1 \frac{1-r^n}{1-r} Use this to find the sum of the first 'n' terms of a geometric series, where a_1 is the first term and 'r' is the common ratio (r ≠ 1). Sum of a Convergent Infinite Geometric Series S = \lim_{n\to\infty} S_n = \frac{a_1}{1-r}, \text{ only if } |r| < 1 If the absolute value of the common ratio 'r' is less than 1, the infinite geometric series converges to this sum. If |r| ≥ 1, the series diverges. The nth-Term Test for...

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Sample Practice Questions

Challenging
Find the sum of the series Σ (2^n + 3^n) / 6^n from n=1 to ∞.
A.1
B.3/2
C.5/6
D.The series diverges.
Challenging
A ball is dropped from a height of 10 meters. Each time it strikes the ground, it bounces back to 3/4 of the previous height. What is the total vertical distance traveled by the ball before it comes to rest?
A.70 m
B.40 m
C.80 m
D.The distance is infinite.
Challenging
Find the sum of the series Σ [arctan(n+1) - arctan(n)] from n=1 to ∞.
A.Ï€/2
B.Ï€
C.The series diverges.
D.Ï€/4

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