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Homework Help: Is the Linear System inconsistent?

  1. Jan 26, 2013 #1
    Hey guys, I'd assume that this will be a very easy answer. I need to clarify what is an inconsistent linear system. I've worked out my matrix and have achieved this form:


    I know that an inconsistent linear system has no solution i.e 0=1. This is throwing me off because of the y components being all zero which means I can make y what ever I want, but does this also make the system inconsistent?
  2. jcsd
  3. Jan 26, 2013 #2


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    x=y=z=w=0 is a solution. It will always be a solution when the RHS is all zeros. You have an infinite number of solutions, but it's not inconsistent. Inconsistent means no solutions.
  4. Jan 26, 2013 #3
    Awesome! Thanks for clearing that up for me!
  5. Jan 26, 2013 #4

    Ray Vickson

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    "Inconsistent" does not apply to homogeneous linear systems (where the right-hand-sides are all zero) because setting all variables = 0 *does* give a solution. No: "consistency" and its opposite are relevant when (some of the) right-hand sides are *nonzero*. For example, the system x = 0 and 2*x = 0 is perfectly consistent, but the system x = 1 and 2*x = 3 is inconsistent.
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