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 equations \[x+3y+5=0\] and \[-3x-9y+2=0\]has:

    A) a unique solution

    B) exactly two solutions

    C) infinitely many solutions 

    D) no solution

    Correct Answer: D

    Solution :

    [d] The given equations are \[x+3y+5=0\] and \[-3x-9y+2=0\].
    Here, \[{{a}_{1}}=1,\,\,{{b}_{1}}=3,\,\,{{c}_{1}}=5,\,\,{{a}_{2}}=-3,\,{{b}_{2}}=-9,\,{{c}_{2}}=2\] Now,   \[\frac{{{a}_{1}}}{{{a}_{2}}}=\frac{-1}{3},\,\frac{{{b}_{1}}}{{{b}_{2}}}=\frac{3}{-9}=\frac{-1}{3}\]and \[\frac{{{c}_{1}}}{{{c}_{2}}}=\frac{5}{2}\]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\frac{{{a}_{1}}}{{{a}_{2}}}=\frac{{{b}_{1}}}{{{b}_{2}}}\ne \frac{{{c}_{1}}}{{{c}_{2}}}\]
    \[\therefore \] The given pair of equations has no solution.


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