JEE Main & Advanced Sample Paper JEE Main - Mock Test - 4

  • question_answer
    The variable plane \[(2\lambda +1)x+(3-\lambda )y+z=4\] always passes through the line

    A)  \[\frac{x}{0}=\frac{y}{0}=\frac{z+4}{1}\]

    B) \[\frac{x}{1}=\frac{y}{2}=\frac{z}{-3}\]

    C) \[\frac{x}{1}=\frac{y}{1}=\frac{z-4}{-7}\]

    D) None of these

    Correct Answer: D

    Solution :

    [d] The plane is \[x+3y+z-4+\lambda (2x-y)=0\] This always passes through the intersection of the planes \[x+3y+z-4=0\]and \[2x-y=0,\] which is a line. Now, \[2x-y=0\] \[\Rightarrow \,\,\,\frac{x}{1}=\frac{y}{2}\]             \[\therefore \,\,\,x+3y+z-4=0\] \[\Rightarrow \,\,\,x+3\times 2x+z-4=0\] \[\Rightarrow \,\,\,7x+z-4=0\] \[\therefore \,\,\,\,7x=-(z-4)\] \[\Rightarrow \,\,\,\frac{x}{1}=\frac{z-4}{-7}\] Hence, line is \[\frac{x}{1}=\frac{y}{2}=\frac{z-4}{-7}.\]


You need to login to perform this action.
You will be redirected in 3 sec spinner