Find the sum S of the infinite series Σk=2∞ 2·(−2/3)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 2r = −2/3k₀ = 2
S =
2.Easy
Find the sum S of the infinite series Σk=0∞ 8·(3/5)ᵏ.
a = 8r = 3/5k₀ = 0
S =
3.Medium
Find the sum S = Σk=1∞ 1/(k(k + 4)).
ak = 1/(k(k + 4))
S =
4.Medium
Exactly one of the four series diverges. Click it.
A: Σ k³/2ᵏB: Σ (1 + 1/k)ᵏC: Σ 3/k⁴D: Σ (−1)ᵏ/√k
- 1A: Σ k³/2ᵏ
- 2B: Σ (1 + 1/k)ᵏ
- 3C: Σ 3/k⁴
- 4D: Σ (−1)ᵏ/√k
5.Hard
f(x) = cos x is approximated by its Maclaurin polynomial of degree 4 at x = 0.8. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = 1 to find the largest possible error |R₄|.
f(x) = cos xn = 4x = 0.8M = 1
|R₄| =
6.Hard
f(x) = eˣ 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 = 2, find the smallest degree n that guarantees an error below 0.001.
f(x) = eˣx = 0.5M = 2ε = 0.001
n =
Answer key
- 1. S = 0.5333
- 2. S = 20
- 3. S = 0.5208
- 4. B: Σ (1 + 1/k)ᵏ
- 5. |R₄| = 0.002731
- 6. n = 4
Full step-by-step solutions: practise this topic on examproblems.com.