Leonhard Euler · 1748 · Internet Archive
Introductio in analysin infinitorum
All 320 leaves · leaf 320
Transcription
290 DE USU SERIERUM RECURRENTIUM
LIB. I. majus quadrato radicis maximæ. Sin autem binæ ejusmodi
infint radices imaginariæ, ut earum productum adæquet vel
adeo superet quadratum maximæ radicis realis, tum investiga-
tio ante exposita nihil declarabit, propterea quod Potestas
$p^n$, præ simili Potestate radicis maximæ nunquam evanescit,
etiamfi Series in infinitum continuetur. Cujus exempla illustra-
tionis causa hic adjicere visum est.
EXEMPLUM I.
Sit proposita æquatio $x^3 - 2x - 4 = 0$, cujus radicem ma-
ximam investigari oporteat.
Resolvitur hæc æquatio in duos Factores $(x-2)(x^2+2x+2)$; unde unam habet radicem realem $2$ & duas reliquas
imaginarias, quarum productum est $2$, minus quam quadratum
radicis realis. Quam ob rem ea per modum hactenus traditum
cognosci poterit. Formetur ergo Series recurrens ex scala re-
lationis $0, +2, +4$, quæ erit
$1, 0, 2, 4, 4, 16, 24, 48, 112, 192
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