Find the sum S6 of the first 6 terms of the geometric sequence 2, 4, 8, …
Sequences & series worksheet with answers
1.Easy
a₁ = 2r = 2n = 6
S6 =
2.Easy
Find the sum S15 of the first 15 terms of the arithmetic sequence −9, −5, −1, 3, …
a₁ = −9d = 4n = 15
S15 =
3.Medium
The power series Σk=1∞ k!·(x + 2)ᵏ/kᵏ converges on an interval around x₀ = −2. Find the left end x of that interval.
Σ k!·(x + 2)ᵏ/kᵏx₀ = −2
x =
4.Medium
Apply the root test to Σk=1∞ ((2k + 3)/(3k + 1))ᵏ. Find L = lim |ak|1/k.
ak = ((2k + 3)/(3k + 1))ᵏ
L =
5.Hard
Recognise the series and find its sum: S = Σk=1∞ k·0.2ᵏ.
ak = k·0.2ᵏ
S =
6.Hard
Find the coefficient c₂ of (x − 1)² in the Taylor series of f(x) = ln x about a = 1.
f(x) = ln xa = 1k = 2
c₂ =
Answer key
- 1. S6 = 126
- 2. S15 = 285
- 3. x = −4.718
- 4. L = 0.6667
- 5. S = 0.3125
- 6. c₂ = −0.5
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