Find the sum S7 of the first 7 terms of the geometric sequence 2, 3, 4.5, …
Sequences & series worksheet with answers
1.Easy
a₁ = 2r = 1.5n = 7
S7 =
2.Easy
A ball is dropped and its first rebound reaches 5 m. Every next rebound reaches 60% of the previous one. Which rebound n is the first one lower than 0.1 m?
a₁ = 5r = 0.6ε = 0.1
n =
3.Medium
Exactly one of the four series diverges. Click it.
A: Σ 2/k⁴B: Σ (1/3)ᵏC: Σ 1/(3k + 5)D: Σ 1/(3ᵏ + k)
- 1A: Σ 2/k⁴
- 2B: Σ (1/3)ᵏ
- 3C: Σ 1/(3k + 5)
- 4D: Σ 1/(3ᵏ + k)
4.Medium
Apply the ratio test to Σk=1∞ k·3ᵏ/5ᵏ. Find L = lim |ak+1/ak|.
ak = k·3ᵏ/5ᵏ
L =
5.Hard
f(x) = sin x is approximated at x = 1.5 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 0.0005.
f(x) = sin xx = 1.5M = 1ε = 0.0005
n =
6.Hard
Use the Maclaurin polynomial of degree 3 of f(x) = ln(1 + x) to approximate f(0.5). Give P₃(0.5).
f(x) = ln(1 + x)n = 3x = 0.5
P₃(0.5) =
Answer key
- 1. S7 = 64.34
- 2. n = 9
- 3. C: Σ 1/(3k + 5)
- 4. L = 0.6
- 5. n = 8
- 6. P₃(0.5) = 0.4167
Full step-by-step solutions: practise this topic on examproblems.com.