10th Class Mathematics Pair of Linear Equations in Two Variables Question Bank Case Based (MCQs) - Pair of Linear Equations in Two Variables

  • question_answer
    If the graphs of the equations in the given situation are plotted on the same graph paper, then:     

    A) The lines will be parallel

    B) The lines will coincide

    C) The lines will intersect

    D) Can't say

    Correct Answer: C

    Solution :

    We can find whether lines will be intersecting, coincident or parallel, by calculating the ratios of the coefficients of the pair of linear equations.                              
    As the two equations are given by           
                \[x-y=4\]          
    and      \[3x-y=24\]      
    Let us calculate the ratios of their coefficients
    \[\frac{{{a}_{1}}}{{{a}_{2}}}=\frac{1}{3};\,\,\frac{{{b}_{1}}}{{{b}_{2}}}=\frac{-1}{-1}=1,\,\,\,\frac{{{c}_{1}}}{{{c}_{2}}}=\frac{4}{24}=\frac{1}{6}\]
    As, \[\frac{{{a}_{1}}}{{{a}_{2}}}\ne \,\,\frac{{{b}_{1}}}{{{b}_{2}}},\] the two lines will intersect at a point.
    So, option [c] is correct.


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