SSC Quantitative Aptitude Coordinate Geometry Question Bank Coordinate Geometry and Graphs of Linear Equations (I)

  • question_answer
    The ratio in which the line 3x + y = 9 divides the line made by joining the points (1, 3) and (2, 7), is

    A) 3 : 4 external

    B) 3 : 4 internal

    C) 1 : 4 internal

    D) 4 : 3 internal

    Correct Answer: B

    Solution :

    [b] Let required ratio be k: 1. Then, coordinates of section point are \[\left( \frac{2k+1}{k+1},\frac{7k+3}{k+1} \right).\] But this point lies on \[3x+y-9=0\] \[\therefore \]      \[3\,\left( \frac{2k+1}{k+1} \right)+\left( \frac{7k+3}{k+1} \right)-9=0\] \[\Rightarrow \]   \[6k+3+7k+3-9k9=0\] \[\Rightarrow \]   \[4k-3=0\] \[\Rightarrow \]   \[k=\frac{3}{4}\] \[\therefore \]Required ratio\[=k:1=3/4:1=3:4\]internally


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