Find the sum S of the infinite series Σk=1∞ 4·(−2/5)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 4r = −2/5k₀ = 1
S =
2.Easy
Find the sum S10 of the first 10 terms of the geometric sequence 2, 1.6, 1.28, …
a₁ = 2r = 0.8n = 10
S10 =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ 3ᵏ/k³B: Σ 1/(k² + 3)C: Σ 2/k³D: Σ (−1)ᵏ/√k
- 1A: Σ 3ᵏ/k³
- 2B: Σ 1/(k² + 3)
- 3C: Σ 2/k³
- 4D: Σ (−1)ᵏ/√k
4.Medium
Exactly one of the four series converges. Click it.
A: Σ (3/2)ᵏB: Σ 3ᵏ/k³C: Σ (−1)ᵏ/√kD: Σ 1/√k
- 1A: Σ (3/2)ᵏ
- 2B: Σ 3ᵏ/k³
- 3C: Σ (−1)ᵏ/√k
- 4D: Σ 1/√k
5.Hard
f(x) = eˣ is approximated by its Maclaurin polynomial of degree 2 at x = 1. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = e1 = 2.718 to find the largest possible error |R₂|.
f(x) = eˣn = 2x = 1M = 2.718
|R₂| =
6.Hard
f(x) = eˣ is approximated by its Maclaurin polynomial of degree 2 at x = 0.5. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = e0.5 = 1.649 to find the largest possible error |R₂|.
f(x) = eˣn = 2x = 0.5M = 1.649
|R₂| =
Answer key
- 1. S = −1.143
- 2. S10 = 8.926
- 3. A: Σ 3ᵏ/k³
- 4. C: Σ (−1)ᵏ/√k
- 5. |R₂| = 0.453
- 6. |R₂| = 0.03435
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