Find the sum S of the infinite series Σk=1∞ 8·(4/5)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 8r = 4/5k₀ = 1
S =
2.Easy
Find the sum S of the infinite series Σk=1∞ 18·(−2/5)ᵏ.
a = 18r = −2/5k₀ = 1
S =
3.Medium
Find the sum S = Σk=1∞ 5/(k(k + 2)).
ak = 5/(k(k + 2))
S =
4.Medium
Exactly one of the four series converges. Click it.
A: Σ ln k / kB: Σ (3/2)ᵏC: Σ 1/(k² + 1)D: Σ (2k + 1)/(k + 2)
- 1A: Σ ln k / k
- 2B: Σ (3/2)ᵏ
- 3C: Σ 1/(k² + 1)
- 4D: Σ (2k + 1)/(k + 2)
5.Hard
Recognise the series and find its sum: S = Σk=0∞ 0.5ᵏ/k!.
ak = 0.5ᵏ/k!
S =
6.Hard
f(x) = eˣ is approximated at x = 1 by its Maclaurin polynomial of degree n. With the Lagrange bound M·|x|ⁿ⁺¹/(n + 1)! and M = 3, find the smallest degree n that guarantees an error below 0.001.
f(x) = eˣx = 1M = 3ε = 0.001
n =
Answer key
- 1. S = 32
- 2. S = −5.143
- 3. S = 3.75
- 4. C: Σ 1/(k² + 1)
- 5. S = 1.649
- 6. n = 6
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