JEE Main & Advanced JEE Main Paper (Held On 10-Jan-2019 Morning)

  • question_answer
    A point P moves on the line\[2x-3y+4=0\]. If Q(1, 4) and R (3, - 2) are fixed points, then the locus of the centroid of \[\Delta \,PQR\] is a line- [JEE Main Online Paper (Held On 10-Jan-2019 Morning]

    A) parallel to y-axis                        

    B) with slope \[\frac{2}{3}\]

    C) parallel to x-axis

    D)                  with slope \[\frac{3}{2}\]

    Correct Answer: B

    Solution :

    \[P\left( h,\,\,\frac{2h+4}{3} \right)\] \[Q\text{ }\left( 1,\text{ }4 \right)\text{ }Q\left( 3,\text{ }-2 \right)\] Centroid G \[(\alpha ,\,\,\beta )\,\equiv \,\left( \frac{h+4}{3},\,\,\frac{2h+4+12-6}{9} \right)\] \[\alpha \,=\,\frac{h+4}{3};\,\,\beta =\frac{2h+10}{9};\,\,\beta \,=\,\frac{2(3\alpha -4)+10}{9};\]\[9\beta =6\alpha +2\] Locus \[\alpha \,=\,x;\,\,\beta =y;\,\,y=\frac{2}{3}x+\frac{2}{9}\] Slope \[=\frac{2}{3}\]


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