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→Простейшие свойства интеграла векторного поля по кусочно-гладкому пути
1) Линейность по векторному полю: <tex> I(\alpha V_1 + \beta V_2, \gamma) = \alpha I(V_1, \gamma) + \beta I(V_2, \gamma) </tex>.
2) Аддитивность при дроблении пути: <tex> \gamma : [a, b] \to \mathbb{R}^m; \ c \in [a, b] </tex> <tex> \gamma_1 : [a, c] \to \mathbb{R}^m; \ t \mapsto \gamma(t); \ \gamma_2 : [c, b] \to \mathbb{R}^m </tex> <tex> I(V, \gamma) = I(V, \gamma_1) + I(V, \gamma_2) </tex>. <tex> \int_{a}^{b} ... = \int_a^c + \int_c^b </tex> 3) Замена параметра: если <tex> \varphi: [p; q] \to [a; b] </tex> — гладкая, <tex> \varphi(p) = a, \ \varphi(q) = b </tex>, <tex> \gamma: [a; b] \to \mathbb{R}^m </tex>, <tex> \tilde{\gamma} = \gamma \circ \varphi: [p; q] \to \mathbb{R}^m </tex>, то <tex> s \mapsto \gamma(\varphi(s)) </tex> Тогда <tex> I(V, \gamma) = I(V, \tilde{\gamma}) </tex>. <tex> I(V, \gamma) = \int_a^b \langle V(\gamma(t)), \gamma'(t) \rangle dt =_{t = \varphi(s)} </tex><tex> \int_a^b \langle V (\gamma(\varphi (s))), \gamma'(\varphi (s)) \varphi'(s) \rangle ds = \int_p^q \langle V(\tilde{\gamma}(s)), \tilde{\gamma}'(s) \rangle ds </tex>
4) Пусть <tex> \gamma_1: [a; b] \to \mathbb{R}^m, \ \gamma_2: [c; d] \to \mathbb{R}^m, \ \gamma_1(b) = \gamma_2(c), \ \gamma = \gamma_2 \gamma_1 </tex> — произведение путей:
<tex> \gamma: [a; b + d - c] \to \mathbb{R}^m = \begin{cases}
\gamma_1(t), \ t \in [a; b] \\
\gamma_2(t - b + c), \ t \in [ab; b + d - c]\end{cases} </tex> то <tex> I(V, \gamma_2 \gamma_1) = I(V, \gamma_1) + I(V, \gamma_2) </tex>. <tex> \int_a^{b + d - c} \langle V(\gamma(t)), \gamma't \rangle dt = \int_a^b + \int_b^{b + d - c} </tex> \\ заменить параметр <tex> s = t - b + c; s \in [c, d] </tex> <tex> \gamma : [a, b] \to \mathbb{R}^m; \ \gamma_- </tex> — противоположный путь (в обратную сторону) <tex> \gamma_-(t) = \gamma(b + a - t), t \in [a, b] </tex> <tex> I(V, \gamma_-) = -I(V, \gamma) </tex> <tex> \int_a^b \langle V(\gamma(b - a - t)),\gamma_-(t) \rangle dt = \int \langle V (\gamma(s)), \gamma'(s) \rangle ds </tex>
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