Unique solution of an overdetermined system

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SUMMARY

A consistent linear system with more equations than unknowns can have either one unique solution or infinitely many solutions. To determine the number of solutions, one must assess the number of independent equations relative to the number of variables. Specifically, if n represents the number of variables and m denotes the number of independent equations, the condition n ≥ m must hold true. The number of free variables in the system is calculated as n - m, which indicates the degree of freedom in the solutions.

PREREQUISITES
  • Understanding of linear systems and their properties
  • Familiarity with matrix representation of linear equations
  • Knowledge of row reduction techniques
  • Concept of independent equations in linear algebra
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  • Study the process of row-reducing matrices to identify independent equations
  • Learn about the rank of a matrix and its implications for solutions
  • Explore the concept of free variables in linear algebra
  • Investigate the conditions for consistency in linear systems
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Students and professionals in mathematics, particularly those studying linear algebra, as well as engineers and data scientists dealing with systems of equations.

Shaybay92
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If I want to know how many solutions a consistent linear system with more equations than unknowns has, how do I tell? Obviously there is either 1 solution of infinite solutions. Can you have a free variable in this case? I'm confused how to find out whether a system will give a unique solution.
 
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You need to determine how many independent equations there are. If the system really is consistent, then there must be no more independent equations than unknown variables. That is, if n is the number of variables and m is the number of independent equations, then [itex]n\ge m[/itex]. The number of free variables is n- m.

If you write the coefficient matrix for the system and row-reduce, the number of independent equations is the number of non-zero rows.
 

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