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FInd the missing expansion of ∇×(A×B)= In other words, derive the completed identity.

User Tweetysat
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Sure, the operation in this question involves the curl of a cross product of two vectors. In vector calculus, there's a specific identity for this, which is known as the vector triple product rule.

The identity of the equation ∇ × (A × B) is:

∇ × (A × B) = (B · ∇)A – (A · ∇)B

Where:
- ∇ is the del operator
- A and B are vectors (in this case, A = i + j + k and B = 2i + 3j + 4k)
- '×' is the cross product
- '·' is the dot product

Let me break down each term for you:

1. (B · ∇)A represents the dot product of B and ∇ (gradient operator), operating on vector A. The dot product of a vector with the del operator acts on a scalar or vector field resulting in gradient of the field in the direction of the vector.

2. Similarly, (A · ∇)B represents the dot product of A and ∇, operating on vector B.

So in effect, what the formula ∇ × (A × B) = (B · ∇)A – (A · ∇)B is doing, is it's taking the dot product of vector B with the gradient of vector A, and subtracting from it the dot product of vector A with the gradient of vector B, which then results in another vector.

This identity is crucial in simplifying complex mathematical physics problems involving vector fields.

Therefore, ∇ × (A × B) = (B · ∇)A – (A · ∇)B

User Matilde
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