Find the sum S of the infinite series Σk=0∞ 10·(−1/3)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 10r = −1/3k₀ = 0
S =
2.Easy
Find the sum S12 of the first 12 terms of the arithmetic sequence 9, 7, 5, 3, …
a₁ = 9d = −2n = 12
S12 =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ 1/(k(k + 3))B: Σ (−1)ᵏ/kC: Σ (4/5)ᵏD: Σ (4/3)ᵏ
- 1A: Σ 1/(k(k + 3))
- 2B: Σ (−1)ᵏ/k
- 3C: Σ (4/5)ᵏ
- 4D: Σ (4/3)ᵏ
4.Medium
Find the radius of convergence R of the power series Σk=1∞ (2k)!·(x + 1)ᵏ/(k!)².
Σ (2k)!·(x + 1)ᵏ/(k!)²x₀ = −1
R =
5.Hard
f(x) = sin x is approximated by its Maclaurin polynomial of degree 5 at x = 1. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = 1 to find the largest possible error |R₅|.
f(x) = sin xn = 5x = 1M = 1
|R₅| =
6.Hard
f(x) = cos x is approximated by its Maclaurin polynomial of degree 2 at x = 0.8. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = 1 to find the largest possible error |R₂|.
f(x) = cos xn = 2x = 0.8M = 1
|R₂| =
Answer key
- 1. S = 7.5
- 2. S12 = −24
- 3. D: Σ (4/3)ᵏ
- 4. R = 0.25
- 5. |R₅| = 0.001389
- 6. |R₂| = 0.08533
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