Find the sum S6 of the first 6 terms of the geometric sequence 0.5, 0.75, 1.125, …
Sequences & series worksheet with answers
1.Easy
a₁ = 0.5r = 1.5n = 6
S6 =
2.Easy
Find the sum S of the infinite series Σk=1∞ 8·(3/4)ᵏ.
a = 8r = 3/4k₀ = 1
S =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ (2/3)ᵏB: Σ (−1)ᵏ/√kC: Σ 1/(2ᵏ + k)D: Σ 2ᵏ/k³
- 1A: Σ (2/3)ᵏ
- 2B: Σ (−1)ᵏ/√k
- 3C: Σ 1/(2ᵏ + k)
- 4D: Σ 2ᵏ/k³
4.Medium
Find the sum S = Σk=1∞ 1/(k(k + 4)).
ak = 1/(k(k + 4))
S =
5.Hard
Use the Maclaurin polynomial of degree 2 of f(x) = cos(2x) to approximate f(0.5). Give P₂(0.5).
f(x) = cos(2x)n = 2x = 0.5
P₂(0.5) =
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 1 × 10⁻⁶.
f(x) = eˣx = 1M = 3ε = 1 × 10⁻⁶
n =
Answer key
- 1. S6 = 10.39
- 2. S = 24
- 3. D: Σ 2ᵏ/k³
- 4. S = 0.5208
- 5. P₂(0.5) = 0.5
- 6. n = 9
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