Find the sum S5 of the first 5 terms of the geometric sequence 2, 1, 0.5, …
Sequences & series worksheet with answers
1.Easy
a₁ = 2r = 0.5n = 5
S5 =
2.Easy
The geometric sequence aₙ = 8·0.6ⁿ⁻¹ decreases. Find the first index n for which aₙ < 0.2.
a₁ = 8r = 0.6ε = 0.2
n =
3.Medium
Find the sum S = Σk=117 5/(k(k + 1)).
ak = 5/(k(k + 1))n = 17
S =
4.Medium
Find the radius of convergence R of the power series Σk=1∞ k!·xᵏ/kᵏ.
Σ k!·xᵏ/kᵏx₀ = 0
R =
5.Hard
f(x) = sin x is approximated by its Maclaurin polynomial of degree 4 at x = 1.5. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = 1 to find the largest possible error |R₄|.
f(x) = sin xn = 4x = 1.5M = 1
|R₄| =
6.Hard
Find the coefficient c₂ of (x − 1)² in the Taylor series of f(x) = ∛x about a = 1.
f(x) = ∛xa = 1k = 2
c₂ =
Answer key
- 1. S5 = 3.875
- 2. n = 9
- 3. S = 4.722
- 4. R = 2.718
- 5. |R₄| = 0.06328
- 6. c₂ = −0.1111
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