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 term a10 of the arithmetic sequence 5, 6.5, 8, 9.5, …
a₁ = 5d = 1.5n = 10
a10 =
3.Medium
Find the sum S = Σk=1∞ 4/(k(k + 2)).
ak = 4/(k(k + 2))
S =
4.Medium
Apply the ratio test to Σk=1∞ (k!)²·1ᵏ/(2k)!. Find L = lim |ak+1/ak|.
ak = (k!)²·1ᵏ/(2k)!
L =
5.Hard
Recognise the series and find its sum: S = Σk=0∞ (−1)ᵏ/(2k)!.
ak = (−1)ᵏ/(2k)!
S =
6.Hard
Find the coefficient c₄ of (x + 1)⁴ in the Taylor series of f(x) = e3x about a = −1.
f(x) = e3xa = −1k = 4
c₄ =
Answer key
- 1. S9 = 0.668
- 2. a10 = 18.5
- 3. S = 3
- 4. L = 0.25
- 5. S = 0.5403
- 6. c₄ = 0.168
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