Find the sum S of the infinite series Σk=1∞ 9·(−1/3)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 9r = −1/3k₀ = 1
S =
2.Easy
Find the sum S10 of the first 10 terms of the geometric sequence 2, 1, 0.5, …
a₁ = 2r = 0.5n = 10
S10 =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ 1/(k(k + 3))B: Σ 2ᵏ/k!C: Σ (1/3)ᵏD: Σ 5/k
- 1A: Σ 1/(k(k + 3))
- 2B: Σ 2ᵏ/k!
- 3C: Σ (1/3)ᵏ
- 4D: Σ 5/k
4.Medium
Find the sum S = Σk=133 1/(k(k + 1)).
ak = 1/(k(k + 1))n = 33
S =
5.Hard
Use the Maclaurin polynomial of degree 4 of f(x) = cos(3x) to approximate f(−0.5). Give P₄(−0.5).
f(x) = cos(3x)n = 4x = −0.5
P₄(−0.5) =
6.Hard
f(x) = eˣ is approximated by its Maclaurin polynomial of degree 3 at x = 1.5. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = e1.5 = 4.482 to find the largest possible error |R₃|.
f(x) = eˣn = 3x = 1.5M = 4.482
|R₃| =
Answer key
- 1. S = −2.25
- 2. S10 = 3.996
- 3. D: Σ 5/k
- 4. S = 0.9706
- 5. P₄(−0.5) = 0.08594
- 6. |R₃| = 0.9454
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