[微積] curl(curl F), grad(F.G), curl(F ×G)
想請問一下 課本提到以下這三個等式
1) ▽ ×(F ×G) = (▽.G)F + (G.▽)F - (▽.F)G - (F.▽)G
2) ▽(F.G) = F ×(▽ ×G) + G ×(▽ ×F) + (F.▽)G + (G.▽)F
3) ▽ ×(▽ ×F) = ▽(▽.F) - ▽^2 F
有沒有比較有規則的推導方式呢? 除了兩邊展開相等以外?
因為像
▽ ×(▽ψ) = 0, ▽.(F ×G) 等許多等式在 differential forms 的符號下會變成
d^2ψ = 0
▽.(F ×G) (▽ ×F).G - F.(▽ ×G)
d(λ_F ^ λ_G) = dλ_F ^ λ_G - λ_F ^ dλ_G
很有規律...(λ_F, λ_G 是與向量場 F, G 相關連的 1-form)
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