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

  • question_answer
    The pair of linear equations are \[4x-5y-12=0,\,10y+20=8x\]

    A) consistent

    B) inconsistent

    C) can't say

    D) None of these

    Correct Answer: B

    Solution :

    The given pair of linear equations is
    \[4x-5y-12=0\] and \[-8x+10y+20=0\]
    On comparing with standard form of pair of linear equations, we get
    \[{{a}_{1}}=4,\,{{b}_{1}}=-5,\,{{c}_{1}}=-12\]
    and     \[{{a}_{2}}=-8,\,{{b}_{2}}=10,\,{{c}_{2}}=20\]
    Here,   \[\frac{{{a}_{1}}}{{{a}_{2}}}=\frac{4}{-8}=-\frac{1}{2},\frac{{{b}_{1}}}{{{b}_{2}}}=\frac{-5}{10}=-\frac{1}{2}\]
    and    \[\frac{{{c}_{1}}}{{{c}_{2}}}=-\frac{12}{20}=-\frac{3}{5}\]
    \[\because \,\,\,\,\,\frac{{{a}_{1}}}{{{a}_{2}}}=\frac{{{b}_{1}}}{{{b}_{2}}}\ne \frac{{{c}_{1}}}{{{c}_{2}}}\]
    \[\therefore \] Given pair of linear equations is inconsistent.


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