Leonhard Euler · 1748 · Internet Archive
Introductio in analysin infinitorum
All 320 leaves · leaf 99
Transcription
EXPONENTIALIBUS AC LOGARITHMIS. 71
pere, unicus tantum realis consideratur. Sic $a^{\sqrt{7}}$ erit valor CAP. VI. determinatus intra limites $a^2$ & $a^3$ comprehensus.
98. Maxime autem valores quantitatis exponentialis $a^z$ a magnitudine numeri constantis $a$ pendebunt. Si enim fuerit $a=1$, semper erit $a^z = 1$, quicunque valores Exponenti $z$ tribuatur; sin autem fuerit $a > 1$, tum valor ipsius $a^z$ eo erunt majores, quo major numerus loco $z$ substituatur, atque adeo, posito $z=\infty$, in infinitum excrescunt; si fuerit $z=0$, fiet $a^0=1$, &, si fit $z<0$ valores $a^z$ fient unitate minores, quoad posito $z=-\infty$ fiat $a^z=0$. Contrarium evenit si fit $a<1$, verum tamen quantitas affirmativa; tum enim valores ipsius $a^z$ decrescent, crescente $z$ supra $0$; crescent vero, si pro $z$ numeri negativi substituantur. Cum enim fit $a<1$, erit $\frac{1}{a}>1$; posito ergo $\frac{1}{a}=b$; erit $a^z=b^{-z}$, unde posterior casus ex priori dijudicari poterit.
99. Si fit $a=0$, ingens saltus in valoribus ipsius $a^z$ deprehenditur, quamdiu enim fuerit $z$ numerus affirmativus seu major nihilo, erit perpetuo $a^z=0$: si fit $z=0$ erit $a^0=1$; sin autem fuerit $z$ numerus negativus, tum $a^z$ obtinebit valorem infinite magnum. Sit enim $z=-3$; erit $a^z=0^{-3}=\frac{1}{0^3}=\frac{1}{0}$, ideoque infinitum. Multo majores autem saltus occurrent, si quantitas constans $a$ habeat valorem negativum, puta $-2$; tum enim ponendis loco $z$ numeris integris valores ipsius $a^z$ alternatim erunt affirmativi & negativi, ut ex hac Serie intelligitur
$a^{-4}; a^{-3}; a^{-2}; a^{-1}; a^0; a^1; a^2; a^3; a^4;$ &c.
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