The arithmetic sequence −11, −6, −1, 4, … ends with the term 144. How many terms n does it have?
Sequences & series worksheet with answers
1.Easy
a₁ = −11d = 5aₙ = 144
n =
2.Easy
Find the sum S10 of the first 10 terms of the geometric sequence 0.5, 1.5, 4.5, …
a₁ = 0.5r = 3n = 10
S10 =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ k/(k + 2)B: Σ (3/5)ᵏC: Σ 1/k³D: Σ 1/(k² + 2)
- 1A: Σ k/(k + 2)
- 2B: Σ (3/5)ᵏ
- 3C: Σ 1/k³
- 4D: Σ 1/(k² + 2)
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 at x = 0.5 by its Maclaurin polynomial of degree n. With the Lagrange bound M·|x|ⁿ⁺¹/(n + 1)! and M = 1, find the smallest degree n that guarantees an error below 1 × 10⁻⁵.
f(x) = sin xx = 0.5M = 1ε = 1 × 10⁻⁵
n =
6.Hard
f(x) = sin x is approximated by its Maclaurin polynomial of degree 2 at x = 0.8. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = 1 to find the largest possible error |R₂|.
f(x) = sin xn = 2x = 0.8M = 1
|R₂| =
Answer key
- 1. n = 32
- 2. S10 = 14762
- 3. A: Σ k/(k + 2)
- 4. R = 2.718
- 5. n = 6
- 6. |R₂| = 0.08533
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