Leonhard Euler · 1744 · Internet Archive
Methodus inveniendi lineas curvas
All 336 leaves · leaf 122
Transcription
AD CURVAS INVENIENDAS ABSOLUTA. 115
valores §.30 indicati substituatur. Quoniam autem insuper in haec differentialia ingrediuntur $d\pi$, $d\pi'$, $d\pi''$, &c. ponamus corum valores ex $n\nu$ oriundos tantisper, donec eos inveniamus, esse hos:
$d\pi = n\nu . \alpha$ $d\pi''' = n\nu . \delta$ $d\pi'''''' = n\nu . \eta$
$d\pi' = n\nu . \beta$ $d\pi'''' = n\nu . \epsilon$ $d\pi''''''' = n\nu . \theta$
$d\pi'' = n\nu . \gamma$ $d\pi''''' = n\nu . \zeta$ &c.
Hinc itaque erunt valores differentiales
$d.Z\,dx = n\nu . dx (L\alpha + \frac{Q}{dx})$
$d.Z'dx = n\nu . dx (L'\beta + \frac{P'}{dx} - \frac{2Q'}{dx^2})$
$d.Z''dx = n\nu . dx (L''\gamma + N' - \frac{P''}{dx} + \frac{Q''}{dx^2})$
$d.Z'''dx = n\nu . dx L'''\delta$
$d.Z''''dx = n\nu . dx L''''\epsilon$
$d.Z'''''dx = n\nu . dx. L'''''\zeta$
&c.
Ut nunc valores litterarum $\alpha$, $\beta$, $\gamma$, $\delta$, $\epsilon$, &c. definiamus; notandum est esse $d\pi$, $d\pi'$, $d\pi''$, &c. valores differentiales quantitatum $\pi$, $\pi'$, $\pi''$, &c. Est vero
$\pi = \int [Z]dx$
$\pi' = \int [Z]dx + \int [Z']dx$
$\pi'' = \int [Z]dx + \int [Z']dx + \int [Z'']dx$
$\pi''' = \int [Z]dx + \int [Z']dx + \int [Z'']dx + \int [Z''']dx$
&c.
ubi $\int [Z]dx$, per hypothesin, a particula $n\nu$ non afficitur. Valores igitur differentiales formularum $[Z]dx$, $[Z']dx$, $[Z'']dx$ &c. sunt investigandi, qui erunt
P 2
$d.[Z]dx$
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