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moe darklight
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Is my proof for "Absolute convergence => Convergence" right?
I had to prove it for my calc test today; my proof looks different than the one my prof posted as the answer; it's also way shorter. He used the one from the book but I didn't memorize it so I used this. Is it right?
Prove that Absolute Convergence implies convergence
Notation:
1. I'm using the notation an means a series. [As in: an = a(1)+a(2)+a(3)...+a(n) and n goes to infinity]
2. |an| means the absolute value of |an|.
***
I. |(-1)^n an| = an.
II. Suppose an converges. i.e: an = C
III. an converges implies that a(n+1) < a(n)
IV. (III.) implies (-1)^n an converges.
QED.
I had to prove it for my calc test today; my proof looks different than the one my prof posted as the answer; it's also way shorter. He used the one from the book but I didn't memorize it so I used this. Is it right?
Homework Statement
Prove that Absolute Convergence implies convergence
The Attempt at a Solution
Notation:
1. I'm using the notation an means a series. [As in: an = a(1)+a(2)+a(3)...+a(n) and n goes to infinity]
2. |an| means the absolute value of |an|.
***
I. |(-1)^n an| = an.
II. Suppose an converges. i.e: an = C
III. an converges implies that a(n+1) < a(n)
IV. (III.) implies (-1)^n an converges.
QED.
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