Prove jacobian matrix is identity of matrix of order 3

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The discussion revolves around proving that the Jacobian matrix Df(x,y,z) for the function f(x,y,z) = xi + yj + zk is the identity matrix of order 3. Participants clarify that the Jacobian matrix can be represented as ((1,0,0),(0,1,0),(0,0,1)), confirming it is indeed a 3x3 identity matrix. The linearity of the D operator is emphasized, with the correct derivatives noted. The conversation concludes with agreement on the identity matrix representation. This confirms the understanding of the Jacobian in relation to linear transformations.
CrimsnDragn
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If f(x,y,z) = xi + yj +zk, prove that Jacobian matrix Df(x,y,z) is the identity matrix of order 3.

Because the D operator is linear, D1f(x,y,z) = i, D2f(x,y,z) = k, D3f(x,y,z) = k

There is clearly a relationship between this and some sort of identity, but I'm not sure how to state it, and I don't understand the order of linear transformations. Could someone help me?
 
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*typo on D2f(x,y,z) = j

actually I was just rethinking about the problem. could Df(x,y,z) = ((1,0,0),(0,1,0),(0,0,1)), which becomes an identity matrix, and the order of 3 refers to 3x3 matrix?
 
CrimsnDragn said:
*typo on D2f(x,y,z) = j

actually I was just rethinking about the problem. could Df(x,y,z) = ((1,0,0),(0,1,0),(0,0,1)), which becomes an identity matrix, and the order of 3 refers to 3x3 matrix?

Yes, exactly.
 
awesome. thanks!
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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