Can Linear Independence be Proven with Given Information?

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SUMMARY

The discussion centers on proving linear independence using the relationship between vectors and a matrix transformation. Specifically, it establishes that if vectors \( u_i = Av_i \) for all \( i \), then the linear combination \( a_1u_1 + a_2u_2 + \cdots + a_nu_n = 0 \) leads to the conclusion that the vectors \( v_i \) are independent if matrix \( A \) is invertible. Conversely, if \( A \) is not invertible, a non-trivial solution exists, demonstrating the dependence of the vectors. This analysis is crucial for understanding linear transformations in linear algebra.

PREREQUISITES
  • Understanding of linear independence and dependence in vector spaces
  • Familiarity with matrix operations and properties of invertible matrices
  • Knowledge of linear transformations and their effects on vector sets
  • Basic proficiency in solving linear equations
NEXT STEPS
  • Study the properties of invertible matrices and their implications on linear transformations
  • Learn about the rank-nullity theorem and its relevance to linear independence
  • Explore examples of linear combinations and their geometric interpretations
  • Investigate the implications of non-invertible matrices on vector spaces and their bases
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Students of linear algebra, educators teaching vector spaces, and anyone interested in the mathematical foundations of linear transformations and their applications in various fields.

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Homework Statement



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Homework Equations





The Attempt at a Solution



I have no idea how to start. To be linearly independent, c1u1+c2u2+...+cnun = 0 has only trivial solution. But I don't know how can I use the given information to prove that
 
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You are given that u_i= Av_i for all i.

For any linear combination, a_1u_1+ a_2u_2+ \cdot\cdot\cdot a_nu_n= 0 we have a_1Av_1+ a_2Av_2+ \cdot\cdot\cdot a_nAv_n= A(a_1v_1+ a_2v_2+ a_nv_n)= 0.

If A is invertible, we have a_1v_1+ a_2v_2+ \cdot\cdot\cdot+ a_nv_n= 0.

On the other hand, if A is NOT invertible, there exist v_0\ne 0 such that Av_0= 0 (you should show that). Since \{v_1, v_2, \cdot\cdot\cdot, v_n\} are n independent vectors in R^n, we can write v_0= c_1v_1+ c_2v_2+ \cdot\cdot\cdot+ c_nv_n for some numbers c_n. Apply A to both sides of that equation.
 

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