The arithmetic sequence −1, 4, 9, 14, … ends with the term 164. How many terms n does it have?
Sequences & series worksheet with answers
1.Easy
a₁ = −1d = 5aₙ = 164
n =
2.Easy
Find the sum S5 of the first 5 terms of the geometric sequence 0.5, 0.75, 1.125, …
a₁ = 0.5r = 1.5n = 5
S5 =
3.Medium
Apply the ratio test to Σk=1∞ k·5ᵏ/3ᵏ. Find L = lim |ak+1/ak|.
ak = k·5ᵏ/3ᵏ
L =
4.Medium
Exactly one of the four series diverges. Click it.
A: Σ k/5ᵏB: Σ 1/(k(k + 3))C: Σ (−1)ᵏ/kD: Σ (1 + 1/k)ᵏ
- 1A: Σ k/5ᵏ
- 2B: Σ 1/(k(k + 3))
- 3C: Σ (−1)ᵏ/k
- 4D: Σ (1 + 1/k)ᵏ
5.Hard
Recognise the series and find its sum: S = Σk=0∞ (−1)ᵏ·0.52k/(2k)!.
ak = (−1)ᵏ·0.52k/(2k)!
S =
6.Hard
f(x) = cos x is approximated by its Maclaurin polynomial of degree 3 at x = 1.5. Use the Lagrange error bound M·|x|ⁿ⁺¹/(n + 1)! with M = 1 to find the largest possible error |R₃|.
f(x) = cos xn = 3x = 1.5M = 1
|R₃| =
Answer key
- 1. n = 34
- 2. S5 = 6.594
- 3. L = 1.667
- 4. D: Σ (1 + 1/k)ᵏ
- 5. S = 0.8776
- 6. |R₃| = 0.2109
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