10th Class Mathematics Pair of Linear Equations in Two Variables Question Bank MCQs - Pair of Linear Equations in Two Variables

  • question_answer
    The values of k for which the system of equations \[x+ky=0,\] \[2x-y=0\] has unique solution, is/are:

    A) \[k=2\]

    B) \[k=-3\]

    C) \[k\ne \frac{-15}{2}\]

    D) \[k\ne \frac{-1}{2}\]

    Correct Answer: D

    Solution :

    [d] Given, \[x+ky=0\] and \[2x-y=0\]
    Here,  \[{{a}_{1}}=1,\,{{b}_{1}}=k,\,{{c}_{1}}=0\]
    and   \[{{a}_{2}}=2,\,{{b}_{2}}=-1,\,{{c}_{2}}=0\]
    System of equations has unique solution
    \[\therefore \,\,\,\,\,\,\,\,\,\,\,\frac{{{a}_{1}}}{{{a}_{2}}}\ne \frac{{{b}_{1}}}{{{b}_{2}}}\,\,\,\,\,\,\,\Rightarrow \,\,\,\,\frac{1}{2}\ne \frac{k}{-1}\,\,\,\,\,\,\,\,\,\,\Rightarrow \,\,\,\,k\ne -\frac{1}{2}\]


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