Find the sum S8 of the first 8 terms of the geometric sequence 10, 8, 6.4, …
Sequences & series worksheet with answers
1.Easy
a₁ = 10r = 0.8n = 8
S8 =
2.Easy
Find the sum S of the infinite series Σk=1∞ 9·(−2/5)ᵏ.
a = 9r = −2/5k₀ = 1
S =
3.Medium
Find the sum S = Σk=1∞ 2/(k(k + 3)).
ak = 2/(k(k + 3))
S =
4.Medium
The power series Σk=1∞ k·2ᵏ·(x − 2)ᵏ converges on an interval around x₀ = 2. Find the left end x of that interval.
Σ k·2ᵏ·(x − 2)ᵏx₀ = 2
x =
5.Hard
Find the coefficient c₂ of (x − 2)² in the Taylor series of f(x) = e−x about a = 2.
f(x) = e−xa = 2k = 2
c₂ =
6.Hard
Recognise the series and find its sum: S = Σk=0∞ (−1)ᵏ·0.52k/(2k)!.
ak = (−1)ᵏ·0.52k/(2k)!
S =
Answer key
- 1. S8 = 41.61
- 2. S = −2.571
- 3. S = 1.222
- 4. x = 1.5
- 5. c₂ = 0.06767
- 6. S = 0.8776
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