Find the sum S9 of the first 9 terms of the geometric sequence 1, −0.5, 0.25, …
Sequences & series worksheet with answers
1.Easy
a₁ = 1r = −0.5n = 9
S9 =
2.Easy
Find the sum S5 of the first 5 terms of the geometric sequence 2, −4, 8, …
a₁ = 2r = −2n = 5
S5 =
3.Medium
Find the radius of convergence R of the power series Σk=1∞ xᵏ/(k·4ᵏ).
Σ xᵏ/(k·4ᵏ)x₀ = 0
R =
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) = ln(1 + x) is approximated by its Maclaurin polynomial of degree 5 at x = 0.5. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = 5! = 120 to find the largest possible error |R₅|.
f(x) = ln(1 + x)n = 5x = 0.5M = 120
|R₅| =
6.Hard
Use the Maclaurin polynomial of degree 3 of f(x) = 1/(1 − x) to approximate f(0.4). Give P₃(0.4).
f(x) = 1/(1 − x)n = 3x = 0.4
P₃(0.4) =
Answer key
- 1. S9 = 0.668
- 2. S5 = 22
- 3. R = 4
- 4. R = 2.718
- 5. |R₅| = 0.002604
- 6. P₃(0.4) = 1.624
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