Find the sum S of the infinite series Σk=2∞ 8·(−1/3)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 8r = −1/3k₀ = 2
S =
2.Easy
Find the sum S7 of the first 7 terms of the geometric sequence 2, −1, 0.5, …
a₁ = 2r = −0.5n = 7
S7 =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ 1/(3ᵏ + k)B: Σ (1/3)ᵏC: Σ (−1)ᵏ/kD: Σ k!/3ᵏ
- 1A: Σ 1/(3ᵏ + k)
- 2B: Σ (1/3)ᵏ
- 3C: Σ (−1)ᵏ/k
- 4D: Σ k!/3ᵏ
4.Medium
Find the sum S = Σk=1∞ 12/(k(k + 2)).
ak = 12/(k(k + 2))
S =
5.Hard
Recognise the series and find its sum: S = Σk=0∞ (−1)ᵏ·1.52k+1/(2k + 1)!.
ak = (−1)ᵏ·1.52k+1/(2k + 1)!
S =
6.Hard
f(x) = sin x is approximated by its Maclaurin polynomial of degree 5 at x = 0.5. 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 = 0.5M = 1
|R₅| =
Answer key
- 1. S = 0.6667
- 2. S7 = 1.344
- 3. D: Σ k!/3ᵏ
- 4. S = 9
- 5. S = 0.9975
- 6. |R₅| = 2.17 × 10⁻⁵
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