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  3. 9th Class
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  5. Linear Equations in Two Variables

9th Class Mathematics Linear Equations in Two Variables Question Bank Linear Equation in two Variables

  • question_answer
    If \[\left( \mathbf{x},\mathbf{y} \right)=\left( \mathbf{8},\mathbf{2} \right)\] is the solution of the pair of linear equations \[\mathbf{mx}+\mathbf{y}=\mathbf{2x}+\mathbf{m}=\mathbf{10},\]then \[\mathbf{m}+\mathbf{n}\] is equal to

    A)  -2     

    B)  -1

    C)  2                                

    D)  1

    Correct Answer: A

    Solution :

    (a): Given, \[\left( x,y \right)=\left( 8,2 \right)\] and \[mx+y=2x+2n=10\] \[\therefore m\left( 8 \right)+2=2\times 8+n=10\] \[\therefore \]\[8m+2=10\text{ }and\text{ }16+n=10\] \[\Rightarrow \]\[m=1\text{ }and\text{ }n=-3\] \[\therefore \]\[m+n-1-3=2\]                                


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