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## Main Question or Discussion Point

Hi, I don't understand why in some texts they put that infinitesimal volume dV = dx dy dz. If V = x y z, infinitesimal volume should be dV = y z dx + x z dy + x y dz, by partial differentiation. Thanks

- Thread starter girolamo
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Hi, I don't understand why in some texts they put that infinitesimal volume dV = dx dy dz. If V = x y z, infinitesimal volume should be dV = y z dx + x z dy + x y dz, by partial differentiation. Thanks

- #2

Mark44

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Because the dimensions of the box are dx, dy, and dz. The volume of this box is dV, which is dx * dy * dz.Hi, I don't understand why in some texts they put that infinitesimal volume dV = dx dy dz.

This would be the change in volume of a box whose dimensions are x, y, and z, and whose dimensions change by dx, dy, and dz.If V = x y z, infinitesimal volume should be dV = y z dx + x z dy + x y dz, by partial differentiation. Thanks

- #3

SteamKing

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It's for the same reason that dA = dx*dy.Hi, I don't understand why in some texts they put that infinitesimal volume dV = dx dy dz. If V = x y z, infinitesimal volume should be dV = y z dx + x z dy + x y dz, by partial differentiation. Thanks

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lavinia

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