Find the sum S6 of the first 6 terms of the geometric sequence 0.5, −0.25, 0.125, …
Sequences & series worksheet with answers
1.Easy
a₁ = 0.5r = −0.5n = 6
S6 =
2.Easy
Find the sum S of the infinite series Σk=0∞ 6·(−1/3)ᵏ.
a = 6r = −1/3k₀ = 0
S =
3.Medium
Find the radius of convergence R of the power series Σk=1∞ k!·xᵏ/kᵏ.
Σ k!·xᵏ/kᵏx₀ = 0
R =
4.Medium
Exactly one of the four series converges. Click it.
A: Σ (2k + 1)/(k + 2)B: Σ (5/4)ᵏC: Σ 3ᵏ/k³D: Σ 1/k²
- 1A: Σ (2k + 1)/(k + 2)
- 2B: Σ (5/4)ᵏ
- 3C: Σ 3ᵏ/k³
- 4D: Σ 1/k²
5.Hard
Recognise the series and find its sum: S = Σk=1∞ k·0.25ᵏ.
ak = k·0.25ᵏ
S =
6.Hard
f(x) = sin x is approximated by its Maclaurin polynomial of degree 2 at x = 0.3. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = 1 to find the largest possible error |R₂|.
f(x) = sin xn = 2x = 0.3M = 1
|R₂| =
Answer key
- 1. S6 = 0.3281
- 2. S = 4.5
- 3. R = 2.718
- 4. D: Σ 1/k²
- 5. S = 0.4444
- 6. |R₂| = 0.0045
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