Question:

If \((a,b,c)\) are the direction ratios of a line joining the points \((4,3,-5)\) and \((-2,1,-8)\), then the point \(P(a,3b,2c)\) lies on the plane

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Direction ratios of the line joining \((x_1,y_1,z_1)\) and \((x_2,y_2,z_2)\) are \((x_2-x_1,\;y_2-y_1,\;z_2-z_1)\).
Updated On: Jun 15, 2026
  • \(x+y+z=0\)
  • \(x+y-2z=0\)
  • \(x+2y+3z=0\)
  • \(x-2y+3z=0\)
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The Correct Option is B

Solution and Explanation

Step 1: Find the direction ratios of the line.
The given points are
\[ A(4,3,-5) \] and
\[ B(-2,1,-8) \]
Direction ratios are obtained by subtracting corresponding coordinates:
\[ a=-2-4=-6 \] \[ b=1-3=-2 \] \[ c=-8-(-5)=-3 \]
Thus, one set of direction ratios is
\[ (a,b,c)=(-6,-2,-3) \]

Step 2: Find the coordinates of point \(P\).
Given,
\[ P(a,3b,2c) \]
Substitute the values of \(a,b,c\):
\[ P=(-6,3(-2),2(-3)) \]
\[ P=(-6,-6,-6) \]

Step 3: Check which plane satisfies the point.
For plane
\[ x+y-2z=0, \] substitute \((-6,-6,-6)\):
\[ -6+(-6)-2(-6) \]
\[ =-12+12 \]
\[ =0 \]
Hence, the point satisfies the plane equation.

Step 4: Final conclusion.
Therefore, the point \(P(a,3b,2c)\) lies on the plane
\[ \boxed{x+y-2z=0} \]
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