Find the sum S19 of the first 19 terms of the arithmetic sequence 7, 4, 1, −2, …
Sequences & series worksheet with answers
1.Easy
a₁ = 7d = −3n = 19
S19 =
2.Easy
Find the sum S of the infinite series Σk=0∞ 12·(1/4)ᵏ.
a = 12r = 1/4k₀ = 0
S =
3.Medium
Find the radius of convergence R of the power series Σk=1∞ 5ᵏ·(x − 3)ᵏ/(k + 1).
Σ 5ᵏ·(x − 3)ᵏ/(k + 1)x₀ = 3
R =
4.Medium
Exactly one of the four series diverges. Click it.
A: Σ 1/(k² + 2)B: Σ (4/5)ᵏC: Σ k³/3ᵏD: Σ 1/(3k + 1)
- 1A: Σ 1/(k² + 2)
- 2B: Σ (4/5)ᵏ
- 3C: Σ k³/3ᵏ
- 4D: Σ 1/(3k + 1)
5.Hard
Find the coefficient c₄ of (x − 1)⁴ in the Taylor series of f(x) = ln x about a = 1.
f(x) = ln xa = 1k = 4
c₄ =
6.Hard
Recognise the series and find its sum: S = Σk=0∞ (−1)ᵏ·0.52k+1/(2k + 1)!.
ak = (−1)ᵏ·0.52k+1/(2k + 1)!
S =
Answer key
- 1. S19 = −380
- 2. S = 16
- 3. R = 0.2
- 4. D: Σ 1/(3k + 1)
- 5. c₄ = −0.25
- 6. S = 0.4794
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