Find the sum S8 of the first 8 terms of the arithmetic sequence 0, 3, 6, 9, …
Sequences & series worksheet with answers
1.Easy
a₁ = 0d = 3n = 8
S8 =
2.Easy
Find the sum S10 of the first 10 terms of the geometric sequence 5, −15, 45, …
a₁ = 5r = −3n = 10
S10 =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ (5/4)ᵏB: Σ k/3ᵏC: Σ 1/(k² + 8)D: Σ (3/4)ᵏ
- 1A: Σ (5/4)ᵏ
- 2B: Σ k/3ᵏ
- 3C: Σ 1/(k² + 8)
- 4D: Σ (3/4)ᵏ
4.Medium
Apply the ratio test to Σk=1∞ kᵏ/(3ᵏ·k!). Find L = lim |ak+1/ak|.
ak = kᵏ/(3ᵏ·k!)
L =
5.Hard
f(x) = cos 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 0.0001.
f(x) = cos xx = 0.5M = 1ε = 0.0001
n =
6.Hard
Use the Maclaurin polynomial of degree 4 of f(x) = eˣ to approximate f(−1.5). Give P₄(−1.5).
f(x) = eˣn = 4x = −1.5
P₄(−1.5) =
Answer key
- 1. S8 = 84
- 2. S10 = −73810
- 3. A: Σ (5/4)ᵏ
- 4. L = 0.9061
- 5. n = 5
- 6. P₄(−1.5) = 0.2734
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