Find the term a12 of the arithmetic sequence −1, 5, 11, 17, …
Sequences & series worksheet with answers
1.Easy
a₁ = −1d = 6n = 12
a12 =
2.Easy
Find the sum S6 of the first 6 terms of the geometric sequence 0.5, 0.25, 0.125, …
a₁ = 0.5r = 0.5n = 6
S6 =
3.Medium
Exactly one of the four series converges. Click it.
A: Σ (4/3)ᵏB: Σ (−1)ᵏ/kC: Σ ln k / kD: Σ 1/√k
- 1A: Σ (4/3)ᵏ
- 2B: Σ (−1)ᵏ/k
- 3C: Σ ln k / k
- 4D: Σ 1/√k
4.Medium
Apply the ratio test to Σk=1∞ 2ᵏ·k!/kᵏ. Find L = lim |ak+1/ak|.
ak = 2ᵏ·k!/kᵏ
L =
5.Hard
f(x) = sin x is approximated at x = 0.5 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 0.001.
f(x) = sin xx = 0.5M = 1ε = 0.001
n =
6.Hard
Find the coefficient c₄ of (x + 1)⁴ in the Taylor series of f(x) = eˣ about a = −1.
f(x) = eˣa = −1k = 4
c₄ =
Answer key
- 1. a12 = 65
- 2. S6 = 0.9844
- 3. B: Σ (−1)ᵏ/k
- 4. L = 0.7358
- 5. n = 4
- 6. c₄ = 0.01533
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