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QJEEM24Ma442b: JEE Main 2024 Mathematics - Class 12 JEEM24Ma442b Solution: Let the point, on the line passing through the points and ,…

Let the point, on the line passing through the points P(1,−2,3)P(1,-2,3) and Q(5,−4,7)Q(5,-4,7) , farther from the origin and at a distance of 9 units from the point PP , be (α,β,γ)(\alpha, \beta, \gamma) . Then α2+β2+γ2\alpha^2+\beta^2+\gamma^2 is equal to :

Multiple Choice Options

  • A 150
  • B 155
  • C 160
  • D 165

Step-by-Step Verified Solution

Line through PQP Q

x−14=y+2−2=z−34\frac{x-1}{4}=\frac{y+2}{-2}=\frac{z-3}{4}

Any point on PQP Q . be R(4λ+1,−2λ−2,4λ+3)R(4 \lambda+1,-2 \lambda-2,4 \lambda+3)

PR=9P R=9 unit

(PR)2=81(P R)^2=81

(4λ+1−1)2+(−2λ−2+2)2+(4λ+3−3)2=81(4 \lambda+1-1)^2+(-2 \lambda-2+2)^2+(4 \lambda+3-3)^2=81

16λ2+4λ2+16λ2=8116 \lambda^2+4 \lambda^2+16 \lambda^2=81

36λ2=8136 \lambda^2=81

λ=±96=±32\lambda= \pm \frac{9}{6}= \pm \frac{3}{2}

∴R\therefore R can be (7,−5,9)(7,-5,9) or (−5,1,−3)(-5,1,-3)

Distance from origin for both points be 49+25+81\sqrt{49+25+81} and 25+1+9=35\sqrt{25+1+9}=\sqrt{35}

∴\therefore Distance of (7,−5,9)(7,-5,9) is farthest from origin

∴(α,β,γ)=(7,−5,9)\therefore(\alpha, \beta, \gamma)=(7,-5,9)

Now 72+(−5)2+92=1557^2+(-5)^2+9^2=155

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