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

  • question_answer
    The value of a for which the lines \[x=1,\text{ }y=2\] and \[{{a}^{2}}x+2y-20=0\] are concurrent, is

    A) 1

    B) 8

    C) -4

    D) -2

    Correct Answer: C

    Solution :

    Given lines are x = 1, y = 2 and \[{{a}^{2}}x+2y-20=0\]. Since, \[a=1,\,y=2\] and \[{{a}^{2}}x+2y-20=0\]are concurrent, i.e x = 1, y = 2 and \[{{a}^{2}}x+2y-20=0\] having a common solution. So, x = 1, y = 2 is a solution of given equation \[{{a}^{2}}.\,1+2\,.\,2-20=0\Rightarrow {{a}^{2}}-16=0\] \[\Rightarrow \,\,\,\,{{a}^{2}}=16\,\,\,\Rightarrow \,\,a=-4,\,4\]


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