Find the sum S5 of the first 5 terms of the geometric sequence 0.5, 1.5, 4.5, …
Sequences & series worksheet with answers
1.Easy
a₁ = 0.5r = 3n = 5
S5 =
2.Easy
The geometric sequence aₙ = 2·0.6ⁿ⁻¹ decreases. Find the first index n for which aₙ < 0.05.
a₁ = 2r = 0.6ε = 0.05
n =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ 3ᵏ/k²B: Σ 1/k²C: Σ 10ᵏ/k!D: Σ 1/(k(k + 2))
- 1A: Σ 3ᵏ/k²
- 2B: Σ 1/k²
- 3C: Σ 10ᵏ/k!
- 4D: Σ 1/(k(k + 2))
4.Medium
Find the sum S = Σk=1∞ 4/(k(k + 1)).
ak = 4/(k(k + 1))
S =
5.Hard
Find the coefficient c₂ of (x − 4)² in the Taylor series of f(x) = ln x about a = 4.
f(x) = ln xa = 4k = 2
c₂ =
6.Hard
Use the Maclaurin polynomial of degree 3 of f(x) = e−x to approximate f(0.8). Give P₃(0.8).
f(x) = e−xn = 3x = 0.8
P₃(0.8) =
Answer key
- 1. S5 = 60.5
- 2. n = 9
- 3. A: Σ 3ᵏ/k²
- 4. S = 4
- 5. c₂ = −0.03125
- 6. P₃(0.8) = 0.4347
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