Find the sum S12 of the first 12 terms of the arithmetic sequence 10, 6, 2, −2, …
Sequences & series worksheet with answers
1.Easy
a₁ = 10d = −4n = 12
S12 =
2.Easy
Find the sum S27 of the first 27 terms of the arithmetic sequence 0, −2, −4, −6, …
a₁ = 0d = −2n = 27
S27 =
3.Medium
Exactly one of the four series converges. Click it.
A: Σ (k + 5)/k²B: Σ (−1)ᵏ/kC: Σ 1/√kD: Σ (7/4)ᵏ
- 1A: Σ (k + 5)/k²
- 2B: Σ (−1)ᵏ/k
- 3C: Σ 1/√k
- 4D: Σ (7/4)ᵏ
4.Medium
Find the sum S = Σk=1∞ 5/(k(k + 1)).
ak = 5/(k(k + 1))
S =
5.Hard
f(x) = cos x is approximated at x = 2 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 0.0005.
f(x) = cos xx = 2M = 1ε = 0.0005
n =
6.Hard
Find the coefficient c₃ of (x + 1)³ in the Taylor series of f(x) = eˣ about a = −1.
f(x) = eˣa = −1k = 3
c₃ =
Answer key
- 1. S12 = −144
- 2. S27 = −702
- 3. B: Σ (−1)ᵏ/k
- 4. S = 5
- 5. n = 9
- 6. c₃ = 0.06131
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