The arithmetic sequence −3, −2.5, −2, −1.5, … ends with the term 9.5. How many terms n does it have?
Sequences & series worksheet with answers
1.Easy
a₁ = −3d = 0.5aₙ = 9.5
n =
2.Easy
Find the term a23 of the arithmetic sequence −9, −4, 1, 6, …
a₁ = −9d = 5n = 23
a23 =
3.Medium
The power series Σk=1∞ k!·(x − 2)ᵏ/kᵏ converges on an interval around x₀ = 2. Find the right end x of that interval.
Σ k!·(x − 2)ᵏ/kᵏx₀ = 2
x =
4.Medium
Exactly one of the four series converges. Click it.
A: Σ (k + 3)/k²B: Σ 1/(k(k + 4))C: Σ k!/10ᵏD: Σ k/(k + 2)
- 1A: Σ (k + 3)/k²
- 2B: Σ 1/(k(k + 4))
- 3C: Σ k!/10ᵏ
- 4D: Σ k/(k + 2)
5.Hard
Recognise the series and find its sum: S = Σk=1∞ k·0.25ᵏ.
ak = k·0.25ᵏ
S =
6.Hard
Use the Maclaurin polynomial of degree 3 of f(x) = sin x to approximate f(1.5). Give P₃(1.5).
f(x) = sin xn = 3x = 1.5
P₃(1.5) =
Answer key
- 1. n = 26
- 2. a23 = 101
- 3. x = 4.718
- 4. B: Σ 1/(k(k + 4))
- 5. S = 0.4444
- 6. P₃(1.5) = 0.9375
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