Find the sum S9 of the first 9 terms of the geometric sequence 3, 6, 12, …
Sequences & series worksheet with answers
1.Easy
a₁ = 3r = 2n = 9
S9 =
2.Easy
Find the sum S14 of the first 14 terms of the arithmetic sequence 6, 12, 18, 24, …
a₁ = 6d = 6n = 14
S14 =
3.Medium
Exactly one of the four series converges. Click it.
A: Σ 3ᵏ/k³B: Σ 1/(2ᵏ + k)C: Σ k/(k + 1)D: Σ 5/k
- 1A: Σ 3ᵏ/k³
- 2B: Σ 1/(2ᵏ + k)
- 3C: Σ k/(k + 1)
- 4D: Σ 5/k
4.Medium
Find the radius of convergence R of the power series Σk=1∞ k!·(x + 1)ᵏ/kᵏ.
Σ k!·(x + 1)ᵏ/kᵏx₀ = −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
Recognise the series and find its sum: S = Σk=0∞ (−1)ᵏ·22k+1/(2k + 1)!.
ak = (−1)ᵏ·22k+1/(2k + 1)!
S =
Answer key
- 1. S9 = 1533
- 2. S14 = 630
- 3. B: Σ 1/(2ᵏ + k)
- 4. R = 2.718
- 5. |R₅| = 0.001389
- 6. S = 0.9093
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