Find the sum S of the infinite series Σk=0∞ 4·(−2/3)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 4r = −2/3k₀ = 0
S =
2.Easy
Find the sum S10 of the first 10 terms of the geometric sequence 10, 15, 22.5, …
a₁ = 10r = 1.5n = 10
S10 =
3.Medium
Find the sum S = Σk=1∞ 1/(k(k + 4)).
ak = 1/(k(k + 4))
S =
4.Medium
Exactly one of the four series converges. Click it.
A: Σ 2ᵏ/k³B: Σ (5k + 1)/(k + 2)C: Σ 1/(2ᵏ + k)D: Σ (5/4)ᵏ
- 1A: Σ 2ᵏ/k³
- 2B: Σ (5k + 1)/(k + 2)
- 3C: Σ 1/(2ᵏ + k)
- 4D: Σ (5/4)ᵏ
5.Hard
Use the Maclaurin polynomial of degree 4 of f(x) = e3x to approximate f(−0.5). Give P₄(−0.5).
f(x) = e3xn = 4x = −0.5
P₄(−0.5) =
6.Hard
Recognise the series and find its sum: S = Σk=0∞ 1.5ᵏ/k!.
ak = 1.5ᵏ/k!
S =
Answer key
- 1. S = 2.4
- 2. S10 = 1133
- 3. S = 0.5208
- 4. C: Σ 1/(2ᵏ + k)
- 5. P₄(−0.5) = 0.2734
- 6. S = 4.482
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