Infinitely Many Solutions? A Homework Problem to Investigate

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Discussion Overview

The discussion revolves around a homework problem concerning the solutions of the equation A*x = b, where A is a singular n by n matrix. Participants explore whether the statement "If A is a singular n by n matrix, then A*x=b has infinitely many solutions" is true or false, examining different cases based on the value of b.

Discussion Character

  • Homework-related
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant poses a true or false question regarding the solutions of A*x = b when A is singular.
  • Another participant questions whether the zero matrix is singular and if it leads to infinitely many solutions when b is nonzero.
  • A participant outlines different cases: if b = 0, then A*x = 0 has infinitely many solutions if det(A) = 0; if b ≠ 0, the number of solutions can vary depending on determinants.
  • Some participants suggest that the original question lacks specificity regarding the value of b, leading to ambiguity in the answer.

Areas of Agreement / Disagreement

Participants express disagreement regarding the interpretation of the problem, with no consensus on whether the statement is true or false due to the unspecified nature of b.

Contextual Notes

The discussion highlights limitations in the problem's formulation, particularly the lack of clarity about the value of b and its implications on the solution set.

blinder
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I had a homework problem and i was wondering if anyone could help me out with it. It is a true or fasle question that requires explanation whether true or false. It goes like this...If A is a singular n by n matrix, then A*x=b has infinitely many solutions.(True or False)
 
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Is the matrix [itex]N = (0)[/itex] singular? Does [itex]Nx = b[/itex] have infinitely many solutions if b is nonzero?
 
There are several case :

b=0, then Ax=0 has infinitely many solution if det(A)=0

b<>0 then it can have zero or an infinity of solution, depending on the determinants : [tex]det(b|_nA)[/tex]

where [tex]b|_nA[/tex] means : the nth column of A is replace by b.

So the answer is "true and false" because you don't specify enough the question.
 
or you might say the question is meaningless since you do not quantify the letter "b".
 

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