Find the sum S25 of the first 25 terms of the arithmetic sequence 11, 17, 23, 29, …
Sequences & series worksheet with answers
1.Easy
a₁ = 11d = 6n = 25
S25 =
2.Easy
Find the sum S9 of the first 9 terms of the geometric sequence 4, −2, 1, …
a₁ = 4r = −0.5n = 9
S9 =
3.Medium
Exactly one of the four series converges. Click it.
A: Σ 1/√kB: Σ (4/3)ᵏC: Σ (−1)ᵏ/√kD: Σ k!/10ᵏ
- 1A: Σ 1/√k
- 2B: Σ (4/3)ᵏ
- 3C: Σ (−1)ᵏ/√k
- 4D: Σ k!/10ᵏ
4.Medium
Find the radius of convergence R of the power series Σk=1∞ k!·(x − 3)ᵏ/kᵏ.
Σ k!·(x − 3)ᵏ/kᵏx₀ = 3
R =
5.Hard
f(x) = cos x 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 = 1 to find the largest possible error |R₃|.
f(x) = cos xn = 3x = 1.5M = 1
|R₃| =
6.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 =
Answer key
- 1. S25 = 2075
- 2. S9 = 2.672
- 3. C: Σ (−1)ᵏ/√k
- 4. R = 2.718
- 5. |R₃| = 0.2109
- 6. c₄ = −0.01563
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