Q39 / 90 · JEE Main 2022 (25 Jun Shift 2) · Mathematics

Let P be the plane passing through the intersection of the planes r→·i^+3j^-k^=5 and r→·2i^-j^+k^=3, and the point 2,1,-2. Let the position vectors of the points X and Y be i^-2j^+4k^ and 5i^-j^+2k^ respectively. Then the points

  • A
    X and X+Y are on the same side of P
  • B
    Y and Y-X are on the opposite sides of P
  • Correct answer
    C
    X and Y are on the opposite sides of P
  • D
    X+Y and X-Y are on the same side of P

Solution

We know that family of planes equation is given by, P1+λP2=0

⇒x+3y-z-5+λ2x-y+z-3=0

2,1,-2 lies on this plane

∴λ=1⇒ So the equation of required plane is 3x+2y-8=0

Now let P=3x+2y-8=0

So, P1=3×1+2×-2-8=-9

P2=3×5+2-1-8=5

Since P1×P2<0, So X and Y are on the opposite sides of plane P

Hence, the correct answer is option: 'C'.

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