Find the sum S of the infinite series Σk=1∞ 4·(2/5)ᵏ.
Sequences & series worksheet with answers
1.Easy
a = 4r = 2/5k₀ = 1
S =
2.Easy
Find the sum S31 of the first 31 terms of the arithmetic sequence 9, 11.5, 14, 16.5, …
a₁ = 9d = 2.5n = 31
S31 =
3.Medium
Apply the ratio test to Σk=1∞ (k!)²·2ᵏ/(2k)!. Find L = lim |ak+1/ak|.
ak = (k!)²·2ᵏ/(2k)!
L =
4.Medium
Find the sum S = Σk=1∞ 3/(k(k + 2)).
ak = 3/(k(k + 2))
S =
5.Hard
Find the coefficient c₂ of (x − 1)² in the Taylor series of f(x) = √x about a = 1.
f(x) = √xa = 1k = 2
c₂ =
6.Hard
Use the Maclaurin polynomial of degree 5 of f(x) = sin(−x) to approximate f(2.5). Give P₅(2.5).
f(x) = sin(−x)n = 5x = 2.5
P₅(2.5) =
Answer key
- 1. S = 2.667
- 2. S31 = 1442
- 3. L = 0.5
- 4. S = 2.25
- 5. c₂ = −0.125
- 6. P₅(2.5) = −0.7096
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