Find the sum S22 of the first 22 terms of the arithmetic sequence −7, −9, −11, −13, …
Sequences & series worksheet with answers
1.Easy
a₁ = −7d = −2n = 22
S22 =
2.Easy
Find the sum S of the infinite series Σk=2∞ 3·(1/3)ᵏ.
a = 3r = 1/3k₀ = 2
S =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ 2ᵏ/k³B: Σ (−1)ᵏ/√kC: Σ (3/4)ᵏD: Σ 3/k³
- 1A: Σ 2ᵏ/k³
- 2B: Σ (−1)ᵏ/√k
- 3C: Σ (3/4)ᵏ
- 4D: Σ 3/k³
4.Medium
Find the sum S = Σk=1∞ 6/(k(k + 3)).
ak = 6/(k(k + 3))
S =
5.Hard
Recognise the series and find its sum: S = Σk=1∞ (−1)k+1/k.
ak = (−1)k+1/k
S =
6.Hard
f(x) = cos x is approximated at x = 1 by its Maclaurin polynomial of degree n. With the Lagrange bound M·|x|ⁿ⁺¹/(n + 1)! and M = 1, find the smallest degree n that guarantees an error below 0.0001.
f(x) = cos xx = 1M = 1ε = 0.0001
n =
Answer key
- 1. S22 = −616
- 2. S = 0.5
- 3. A: Σ 2ᵏ/k³
- 4. S = 3.667
- 5. S = 0.6931
- 6. n = 7
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