Probably easy proof for you guys

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SUMMARY

The discussion centers on proving the statement that if the cross products of two vectors \(\vec{v}\) and \(\vec{u}\) with a non-zero vector \(\vec{x}\) are equal, then \(\vec{v}\) must equal \(\vec{u}\). A counterexample is provided using \(\vec{x} = \langle -2, 3, 1 \rangle\), \(\vec{u} = \langle 1, 2, 3 \rangle\), and \(\vec{v} = \langle 3, -1, 2 \rangle\), where both cross products yield \(\langle 7, 7, -7 \rangle\), demonstrating that the initial statement is false. The key takeaway is that equal cross products do not imply equality of the original vectors.

PREREQUISITES
  • Understanding of vector operations, specifically the cross product.
  • Familiarity with vector notation and properties in three-dimensional space.
  • Basic knowledge of linear algebra concepts.
  • Ability to manipulate and compute with vectors in \(\mathbb{R}^3\).
NEXT STEPS
  • Study the properties of the cross product in vector algebra.
  • Explore counterexamples in vector calculus to understand the limitations of vector equality.
  • Learn about the geometric interpretation of cross products and their applications.
  • Investigate the implications of vector identities in physics and engineering contexts.
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Students of mathematics, particularly those studying linear algebra, educators teaching vector operations, and anyone interested in the properties of vector calculus.

benhou
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Homework Statement



Prove if [tex]\vec{x}\times\vec{v}=\vec{x}\times \vec{u}[/tex], then [tex]\vec{v}=\vec{u}[/tex]
where [tex]\vec{x}\neq \vec{0}[/tex]

2. The attempt at a solution

Use the definition of cross product and tried to reduce it.
 
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That is false as stated. Let x = <-2, 3, 1>, u = <1,2,3>, v = < 3,-1,2>. Then x cross u and x cross v are both <7,7,-7>. So your first step in solving the problem is to state it correctly.
 

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