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I'm a bit confused as to the following vector calculus identity:

[∇ (∇.A)]_i = (δ/δx_i )( δA_j/δx_j)

Shouldn’t it be = (δ/δx_i )( δA_i/δx_i) why is it ‘j’ if we are taking it over ‘i’ ?

Thanks.

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# Homework Help: Vector Calculus identity

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