Solution of linear equation with variables











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For what values of a and b the following system of linear equations has



2x + 3y + 5z = 9



7x + 3y - 2z = 8



2x + 3y + az = b



a) no solution.
b) a unique solution.
c) an infinite number of solutions.



[I have found the properties of a and b as (a=5, b!=9) for no solution by its determinant. I have tried to find the others but couldn't find a way to write them in logic considering there are two variables. Am I going to write like if a=... then b=... or is there an other way? Is it going to be a=5 b!=9 for a) and a=5 b=9 for c) ?][I am mostly sucked with finding the unique solution set.]










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    up vote
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    down vote

    favorite












    For what values of a and b the following system of linear equations has



    2x + 3y + 5z = 9



    7x + 3y - 2z = 8



    2x + 3y + az = b



    a) no solution.
    b) a unique solution.
    c) an infinite number of solutions.



    [I have found the properties of a and b as (a=5, b!=9) for no solution by its determinant. I have tried to find the others but couldn't find a way to write them in logic considering there are two variables. Am I going to write like if a=... then b=... or is there an other way? Is it going to be a=5 b!=9 for a) and a=5 b=9 for c) ?][I am mostly sucked with finding the unique solution set.]










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      up vote
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      down vote

      favorite









      up vote
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      down vote

      favorite











      For what values of a and b the following system of linear equations has



      2x + 3y + 5z = 9



      7x + 3y - 2z = 8



      2x + 3y + az = b



      a) no solution.
      b) a unique solution.
      c) an infinite number of solutions.



      [I have found the properties of a and b as (a=5, b!=9) for no solution by its determinant. I have tried to find the others but couldn't find a way to write them in logic considering there are two variables. Am I going to write like if a=... then b=... or is there an other way? Is it going to be a=5 b!=9 for a) and a=5 b=9 for c) ?][I am mostly sucked with finding the unique solution set.]










      share|cite|improve this question















      For what values of a and b the following system of linear equations has



      2x + 3y + 5z = 9



      7x + 3y - 2z = 8



      2x + 3y + az = b



      a) no solution.
      b) a unique solution.
      c) an infinite number of solutions.



      [I have found the properties of a and b as (a=5, b!=9) for no solution by its determinant. I have tried to find the others but couldn't find a way to write them in logic considering there are two variables. Am I going to write like if a=... then b=... or is there an other way? Is it going to be a=5 b!=9 for a) and a=5 b=9 for c) ?][I am mostly sucked with finding the unique solution set.]







      vector-spaces






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      edited Nov 15 at 15:42

























      asked Nov 15 at 15:36









      E.Canberk

      13




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          The system has a unique solution if and only if the determinant of the matrix of coefficients is non-zero. In all other cases, it has either no solution or infinitely many solutions. To distinguish the two, find the images of $$left(array{1\0\0}right),left(array{0\1\0}right),mbox{ and } left(array{0\0\1}right)$$ under (the linear map corresponding to) the matrix of coefficients. There are infinitely many solutions exactly when you can write $$left(array{9\8\b}right)$$ as a linear combination of those image vectors, otherwise there are no solutions.






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          • When a=5 the determinant is zero therefore no solution but when b=9, does it still count as no solution because of the determinant or can we say unique solution because 0 = 0 in the given values
            – E.Canberk
            Nov 15 at 15:49










          • The row equivalet form of the matrix = R1(1, -6, -17, -19), R2(0, 15, 39, 47), R3(0, 0, a-5, b-9)
            – E.Canberk
            Nov 15 at 15:51










          • Why would there be a unique solution? You're trying to solve the whole system, not just one dimension of it. And, again, the determinant being zero does not mean that there is no solution. It means that either their is no solution, or there are infinitely many solutions.
            – user3482749
            Nov 15 at 15:55










          • Your last sentence was the answer which I was waiting to confirm my question. And for the first sentence, it asks me the values of a and b such that system has unique solution.
            – E.Canberk
            Nov 15 at 16:01











          Your Answer





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          The system has a unique solution if and only if the determinant of the matrix of coefficients is non-zero. In all other cases, it has either no solution or infinitely many solutions. To distinguish the two, find the images of $$left(array{1\0\0}right),left(array{0\1\0}right),mbox{ and } left(array{0\0\1}right)$$ under (the linear map corresponding to) the matrix of coefficients. There are infinitely many solutions exactly when you can write $$left(array{9\8\b}right)$$ as a linear combination of those image vectors, otherwise there are no solutions.






          share|cite|improve this answer





















          • When a=5 the determinant is zero therefore no solution but when b=9, does it still count as no solution because of the determinant or can we say unique solution because 0 = 0 in the given values
            – E.Canberk
            Nov 15 at 15:49










          • The row equivalet form of the matrix = R1(1, -6, -17, -19), R2(0, 15, 39, 47), R3(0, 0, a-5, b-9)
            – E.Canberk
            Nov 15 at 15:51










          • Why would there be a unique solution? You're trying to solve the whole system, not just one dimension of it. And, again, the determinant being zero does not mean that there is no solution. It means that either their is no solution, or there are infinitely many solutions.
            – user3482749
            Nov 15 at 15:55










          • Your last sentence was the answer which I was waiting to confirm my question. And for the first sentence, it asks me the values of a and b such that system has unique solution.
            – E.Canberk
            Nov 15 at 16:01















          up vote
          0
          down vote













          The system has a unique solution if and only if the determinant of the matrix of coefficients is non-zero. In all other cases, it has either no solution or infinitely many solutions. To distinguish the two, find the images of $$left(array{1\0\0}right),left(array{0\1\0}right),mbox{ and } left(array{0\0\1}right)$$ under (the linear map corresponding to) the matrix of coefficients. There are infinitely many solutions exactly when you can write $$left(array{9\8\b}right)$$ as a linear combination of those image vectors, otherwise there are no solutions.






          share|cite|improve this answer





















          • When a=5 the determinant is zero therefore no solution but when b=9, does it still count as no solution because of the determinant or can we say unique solution because 0 = 0 in the given values
            – E.Canberk
            Nov 15 at 15:49










          • The row equivalet form of the matrix = R1(1, -6, -17, -19), R2(0, 15, 39, 47), R3(0, 0, a-5, b-9)
            – E.Canberk
            Nov 15 at 15:51










          • Why would there be a unique solution? You're trying to solve the whole system, not just one dimension of it. And, again, the determinant being zero does not mean that there is no solution. It means that either their is no solution, or there are infinitely many solutions.
            – user3482749
            Nov 15 at 15:55










          • Your last sentence was the answer which I was waiting to confirm my question. And for the first sentence, it asks me the values of a and b such that system has unique solution.
            – E.Canberk
            Nov 15 at 16:01













          up vote
          0
          down vote










          up vote
          0
          down vote









          The system has a unique solution if and only if the determinant of the matrix of coefficients is non-zero. In all other cases, it has either no solution or infinitely many solutions. To distinguish the two, find the images of $$left(array{1\0\0}right),left(array{0\1\0}right),mbox{ and } left(array{0\0\1}right)$$ under (the linear map corresponding to) the matrix of coefficients. There are infinitely many solutions exactly when you can write $$left(array{9\8\b}right)$$ as a linear combination of those image vectors, otherwise there are no solutions.






          share|cite|improve this answer












          The system has a unique solution if and only if the determinant of the matrix of coefficients is non-zero. In all other cases, it has either no solution or infinitely many solutions. To distinguish the two, find the images of $$left(array{1\0\0}right),left(array{0\1\0}right),mbox{ and } left(array{0\0\1}right)$$ under (the linear map corresponding to) the matrix of coefficients. There are infinitely many solutions exactly when you can write $$left(array{9\8\b}right)$$ as a linear combination of those image vectors, otherwise there are no solutions.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Nov 15 at 15:45









          user3482749

          1,709411




          1,709411












          • When a=5 the determinant is zero therefore no solution but when b=9, does it still count as no solution because of the determinant or can we say unique solution because 0 = 0 in the given values
            – E.Canberk
            Nov 15 at 15:49










          • The row equivalet form of the matrix = R1(1, -6, -17, -19), R2(0, 15, 39, 47), R3(0, 0, a-5, b-9)
            – E.Canberk
            Nov 15 at 15:51










          • Why would there be a unique solution? You're trying to solve the whole system, not just one dimension of it. And, again, the determinant being zero does not mean that there is no solution. It means that either their is no solution, or there are infinitely many solutions.
            – user3482749
            Nov 15 at 15:55










          • Your last sentence was the answer which I was waiting to confirm my question. And for the first sentence, it asks me the values of a and b such that system has unique solution.
            – E.Canberk
            Nov 15 at 16:01


















          • When a=5 the determinant is zero therefore no solution but when b=9, does it still count as no solution because of the determinant or can we say unique solution because 0 = 0 in the given values
            – E.Canberk
            Nov 15 at 15:49










          • The row equivalet form of the matrix = R1(1, -6, -17, -19), R2(0, 15, 39, 47), R3(0, 0, a-5, b-9)
            – E.Canberk
            Nov 15 at 15:51










          • Why would there be a unique solution? You're trying to solve the whole system, not just one dimension of it. And, again, the determinant being zero does not mean that there is no solution. It means that either their is no solution, or there are infinitely many solutions.
            – user3482749
            Nov 15 at 15:55










          • Your last sentence was the answer which I was waiting to confirm my question. And for the first sentence, it asks me the values of a and b such that system has unique solution.
            – E.Canberk
            Nov 15 at 16:01
















          When a=5 the determinant is zero therefore no solution but when b=9, does it still count as no solution because of the determinant or can we say unique solution because 0 = 0 in the given values
          – E.Canberk
          Nov 15 at 15:49




          When a=5 the determinant is zero therefore no solution but when b=9, does it still count as no solution because of the determinant or can we say unique solution because 0 = 0 in the given values
          – E.Canberk
          Nov 15 at 15:49












          The row equivalet form of the matrix = R1(1, -6, -17, -19), R2(0, 15, 39, 47), R3(0, 0, a-5, b-9)
          – E.Canberk
          Nov 15 at 15:51




          The row equivalet form of the matrix = R1(1, -6, -17, -19), R2(0, 15, 39, 47), R3(0, 0, a-5, b-9)
          – E.Canberk
          Nov 15 at 15:51












          Why would there be a unique solution? You're trying to solve the whole system, not just one dimension of it. And, again, the determinant being zero does not mean that there is no solution. It means that either their is no solution, or there are infinitely many solutions.
          – user3482749
          Nov 15 at 15:55




          Why would there be a unique solution? You're trying to solve the whole system, not just one dimension of it. And, again, the determinant being zero does not mean that there is no solution. It means that either their is no solution, or there are infinitely many solutions.
          – user3482749
          Nov 15 at 15:55












          Your last sentence was the answer which I was waiting to confirm my question. And for the first sentence, it asks me the values of a and b such that system has unique solution.
          – E.Canberk
          Nov 15 at 16:01




          Your last sentence was the answer which I was waiting to confirm my question. And for the first sentence, it asks me the values of a and b such that system has unique solution.
          – E.Canberk
          Nov 15 at 16:01


















           

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