If g (0, ∞) → (0, ∞) is continuous with limx→0 g(x) = +∞o and Σ an is converging series with strictly positive terms, then Σ(1/g(an)) is a converging series. Select one: O a. False, here is a counter-example: an = 1/n², g(x) = 1/(nx). O b. True, because limx→o g(x) = +∞o implies g(x) ≥ M/x for some constant number M > 0, so 1/g(an) ≤an/M and, by comparison theorem, 1/g(an) converges. O c. True, because by n-th term test an → 0 and thus, by sequential characterisation of the continuity, 1/g(an) 0, so 1/g(an) must converge. O d. False, here is a counter-example: an = 1/n², g(x)= = x-1/3

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
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If g : (0, ∞) → (0, ∞) is continuous with limx→0 g(x) = +∞o and Σan is converging series with strictly
positive terms, then Σ(1/g(an)) is a converging series.
Select one:
a. False, here is a counter-example: an
=
1/n², g(x) = 1/(nx).
b.
True, because limx→o g(x) = +∞ implies g(x) ≥ M/x for some constant number M > 0, so
1/g(an) ≤ an/M and, by comparison theorem, Σ 1/g(an) converges.
c. True, because by n-th term test an → 0 and thus, by sequential characterisation of the continuity,
1/g(an) → 0, so Σ 1/g(an) must converge.
O d. False, here is a counter-example: an =
x²
= x-1/3.
1/n², g(x) =
Transcribed Image Text:If g : (0, ∞) → (0, ∞) is continuous with limx→0 g(x) = +∞o and Σan is converging series with strictly positive terms, then Σ(1/g(an)) is a converging series. Select one: a. False, here is a counter-example: an = 1/n², g(x) = 1/(nx). b. True, because limx→o g(x) = +∞ implies g(x) ≥ M/x for some constant number M > 0, so 1/g(an) ≤ an/M and, by comparison theorem, Σ 1/g(an) converges. c. True, because by n-th term test an → 0 and thus, by sequential characterisation of the continuity, 1/g(an) → 0, so Σ 1/g(an) must converge. O d. False, here is a counter-example: an = x² = x-1/3. 1/n², g(x) =
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