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2706
notes/notes.pdf
2706
notes/notes.pdf
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@@ -297,4 +297,70 @@ $
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e^x + y dot x + sin y dot x + e^y eq C_2
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$
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=== Интегрирующий множитель
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$
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mu(x, y) - "интегрирующий множитель"
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$
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$
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mu(x, y) dot P(x, y) d x + mu(x, y) dot Q(x, y) d y eq 0
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$
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$
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frac(partial(mu(x, y) dot P(x, y)), partial y) eq frac(partial(mu(x, y) dot Q(x, y)), partial x)
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$
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$
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mu eq mu(x, y), space.quad P eq P(x, y), space.quad Q eq Q(x, y)
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$
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$
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frac(partial M, partial y) dot P + mu dot frac(partial P, partial y) eq frac(partial mu, partial x) dot Q + mu dot frac(partial Q, partial x)
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$
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$
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frac(partial mu, partial y) dot P - frac(partial mu, partial x) dot Q eq mu dot (frac(partial Q, partial x) - frac(partial P, partial y))
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$
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1) Пусть $mu eq mu(x)$
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$
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- frac(d mu, d x) dot Q eq mu dot (frac(partial Q, partial x) - frac(partial P, partial y))
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$
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$
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frac(d mu, mu) eq -1/Q (frac(partial Q, partial x) - frac(partial P, partial y)) dot d x
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$
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$
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ln mu eq integral 1/Q (frac(partial P, partial y) - frac(partial Q, partial x)) dot d x
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$
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$
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mu (x) eq exp(integral underbrace(1/Q (frac(partial P, partial y) - frac(partial Q, partial x)), eq F_1 (x)) dot d x)
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$
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При этом
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$
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1/Q (frac(partial P, partial y) - frac(partial Q, partial x)) eq F_1 (x)
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$
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То есть зависеть только от $x$.
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2) Пусть $mu eq mu(y)$
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Размышляя аналогично, получим формулу
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$
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mu(y) eq exp(integral underbrace(1/P (frac(partial Q, partial x) - frac(partial P, partial y)), eq F_2 (y)) d y)
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$
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При этом
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$
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1/P (frac(partial Q, partial x) - frac(partial P, partial y)) eq F_2 (y)
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$
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То есть зависеть только от $y$.
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@@ -3281,8 +3281,8 @@ endobj
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/Length 5229
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/Filter /FlateDecode
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>>
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stream
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stream
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