Description: Let L be the limit, if one exists, of the ratio ( abs( ( A( k + 1 ) ) / ( Ak ) ) ) (as in the ratio test cvgdvgrat ) as k increases. Then the radius of convergence of power series sum_ n e. NN0 ( ( An ) x. ( x ^ n ) ) is ( 1 / L ) if L is nonzero. Proof "The limit involved in the ratio test..." in https://en.wikipedia.org/wiki/Radius_of_convergence —a few lines that evidently hide quite an involved process to confirm. (Contributed by Steve Rodriguez, 8-Mar-2020)
Ref | Expression | ||
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Hypotheses | radcnvrat.g | |
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radcnvrat.a | |
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radcnvrat.r | |
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radcnvrat.rat | |
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radcnvrat.z | |
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radcnvrat.m | |
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radcnvrat.n0 | |
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radcnvrat.l | |
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radcnvrat.ln0 | |
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Assertion | radcnvrat | |