Find the sum S9 of the first 9 terms of the geometric sequence 0.5, 1.5, 4.5, …
Sequences & series worksheet with answers
1.Easy
a₁ = 0.5r = 3n = 9
S9 =
2.Easy
Find the sum S of the infinite series Σk=0∞ 10·(1/3)ᵏ.
a = 10r = 1/3k₀ = 0
S =
3.Medium
The power series Σk=1∞ (1/2)ᵏ·(x − 2)ᵏ/(k + 1) converges on an interval around x₀ = 2. Find the right end x of that interval.
Σ (1/2)ᵏ·(x − 2)ᵏ/(k + 1)x₀ = 2
x =
4.Medium
Exactly one of the four series diverges. Click it.
A: Σ 3ᵏ/k!B: Σ (−1)ᵏ/kC: Σ 1/(2ᵏ + k)D: Σ (k + 4)/k²
- 1A: Σ 3ᵏ/k!
- 2B: Σ (−1)ᵏ/k
- 3C: Σ 1/(2ᵏ + k)
- 4D: Σ (k + 4)/k²
5.Hard
Find the coefficient c₄ of (x − 2)⁴ in the Taylor series of f(x) = ln x about a = 2.
f(x) = ln xa = 2k = 4
c₄ =
6.Hard
Use the Maclaurin polynomial of degree 5 of f(x) = sin(3x) to approximate f(0.8). Give P₅(0.8).
f(x) = sin(3x)n = 5x = 0.8
P₅(0.8) =
Answer key
- 1. S9 = 4921
- 2. S = 15
- 3. x = 4
- 4. D: Σ (k + 4)/k²
- 5. c₄ = −0.01563
- 6. P₅(0.8) = 0.7596
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