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

  • question_answer
    Find the value(s) of k for which the system of equations \[kx-y=4\] has \[10x-2y=3\]has no solution.                                        

    A) 6

    B) 4

    C) 5

    D) 2

    Correct Answer: C

    Solution :

    [c] The given system of equations is
    \[kx-y-4=0\]
    \[10x-2y-3=0\]                    
    Here, \[{{a}_{1}}=k,\] \[{{b}_{1}}=-1,\] \[{{c}_{1}}=-4\] and \[{{a}_{1}}=10,\,{{b}_{2}}=-2,\,{{c}_{2}}=-3\]
    The given system will have no solution, if                 
    \[\frac{{{a}_{1}}}{{{a}_{2}}}=\frac{{{b}_{1}}}{{{b}_{2}}}\ne \frac{{{c}_{1}}}{{{c}_{2}}}\,\,\,\Rightarrow \,\,\frac{k}{10}=\frac{-1}{-2}\ne \frac{-2}{-3}\]
    \[\Rightarrow \,\,\,\,\,\,\frac{k}{10}=\frac{-1}{-2}\,\,\,\,\,\,\,\,\,\,\,\,\Rightarrow \,\,\,\,\,\,k=\frac{10}{2}\]
    \[\Rightarrow \,\,\,\,\,\,k=5\]
    Hence, the given system will have no solution, if \[k=5.\]


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