Find the sum S of the infinite series Σk=1∞ 9·(1/3)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 9r = 1/3k₀ = 1
S =
2.Easy
A ball is dropped and its first rebound reaches 8 m. Every next rebound reaches 75% of the previous one. Which rebound n is the first one lower than 0.1 m?
a₁ = 8r = 0.75ε = 0.1
n =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ 2/k⁴B: Σ (3/4)ᵏC: Σ ln k / kD: Σ (−1)ᵏ/√k
- 1A: Σ 2/k⁴
- 2B: Σ (3/4)ᵏ
- 3C: Σ ln k / k
- 4D: Σ (−1)ᵏ/√k
4.Medium
Apply the ratio test to Σk=1∞ kᵏ/(5ᵏ·k!). Find L = lim |ak+1/ak|.
ak = kᵏ/(5ᵏ·k!)
L =
5.Hard
Find the coefficient c₂ of (x − 1)² in the Taylor series of f(x) = e−x about a = 1.
f(x) = e−xa = 1k = 2
c₂ =
6.Hard
Recognise the series and find its sum: S = Σk=0∞ (−1)ᵏ·0.82k/(2k)!.
ak = (−1)ᵏ·0.82k/(2k)!
S =
Answer key
- 1. S = 4.5
- 2. n = 17
- 3. C: Σ ln k / k
- 4. L = 0.5437
- 5. c₂ = 0.1839
- 6. S = 0.6967
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