- #1
oblixps
- 38
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[tex] A_{j_{1}...j_{p}} [/tex] is a (0, p) tensor defined in a star shaped region of some point P where the coordinates [tex] x^1 = ... = x^n = 0 [/tex].
in the course of proving Poincare's lemma my book does the following: [tex] \frac{\partial}{\partial x^j}A_{j_{1}...j_{p}}(tx^h) = \frac{\partial A_{j_{1}...j_{p}}}{\partial x^l}\frac{\partial(tx^l)}{\partial x^j} = \frac{\partial A_{j_{1}...j_{p}}}{\partial x^l} t\delta^{l}_{j} = t\frac{\partial A_{j_{1}...j_{p}}}{\partial x^l} [/tex].
what I'm confused about is why didn't the book do [tex] \frac{\partial}{\partial x^j}A_{j_{1}...j_{p}}(tx^h) = \frac{\partial A_{j_{1}...j_{p}}}{\partial (tx^l)}\frac{\partial(tx^l)}{\partial x^j} [/tex].
what happened to that t in the "denominator" of the first fraction in the chain rule?
in the course of proving Poincare's lemma my book does the following: [tex] \frac{\partial}{\partial x^j}A_{j_{1}...j_{p}}(tx^h) = \frac{\partial A_{j_{1}...j_{p}}}{\partial x^l}\frac{\partial(tx^l)}{\partial x^j} = \frac{\partial A_{j_{1}...j_{p}}}{\partial x^l} t\delta^{l}_{j} = t\frac{\partial A_{j_{1}...j_{p}}}{\partial x^l} [/tex].
what I'm confused about is why didn't the book do [tex] \frac{\partial}{\partial x^j}A_{j_{1}...j_{p}}(tx^h) = \frac{\partial A_{j_{1}...j_{p}}}{\partial (tx^l)}\frac{\partial(tx^l)}{\partial x^j} [/tex].
what happened to that t in the "denominator" of the first fraction in the chain rule?