The equation of the plane that contains the line of intersection of the planes. $x+2 y+3 z-4=0$ and $2…

The equation of the plane that contains the line of intersection of the planes. $x+2 y+3 z-4=0$ and $2 x+y+5=0$ and is perpendicular to the plane $5 x+3 y-6 z+8=0$ is
  1. $14 x+7 y-7 z-4=0$
  2. $33 x+45 y+50 z-41=0$
  3. $-33 \mathrm{x}+45-50 \mathrm{z}+41=0$
  4. $5 x+31 y+50 z-41=0$

Solution

The equation of the required plane is $(x+2 y+3 z-4)+\lambda$ $\begin{aligned} & (2 x+y-z+5)=0 \text { i.e. } \\ & (1+2 \lambda) x+(2+\lambda) y+(3-\lambda) z+(-4+5 \lambda)=0 \end{aligned}$ Since (1) is perpendicular to the plane $5 x+3 y-6 z+8=0$, we write $\begin{aligned} & (1+2 \lambda)(5)+(2+\lambda)(3)+(3-\lambda)(-6)=0 \\ & \therefore 5+10 \lambda+6+3 \lambda-18+6 \lambda=0 \\ & 19 \lambda=7 \\ & \Rightarrow \lambda=\frac{7}{19} \end{aligned}$ Substituting value of $\lambda$ in eq. (1), we get $\begin{aligned} & \left(1+\frac{14}{19}\right) \mathrm{x}+\left(2+\frac{7}{19}\right) \mathrm{y}+\left(3-\frac{7}{19}\right) \mathrm{z}+\left(-4+\frac{35}{19}\right)=0 \\ & \therefore 33 \mathrm{x}+45 \mathrm{y}+50 \mathrm{z}-41=0 \end{aligned}$

Asked in: MHT CET 2021 (20 Sep Shift 2)

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