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1)

If the line, x32=y+21=z+43 lies in the plane, lx+my-z=9, then  l2+m2 is equal to


A) 26

B) 18

C) 5

D) 2

Answer:

Option D

Explanation:

Since, the line x32=y+21=z+43 lies in the plane, lx+my-z=9, therefore we have 2l-m-3=0

 [  normal  will be perpendicular to the line]

   2lm=3          .......(i)

   and  3l2m+4=9

   [point(3,2,4) lies  on the plane]

3l2m=5     ........(ii)

On solvubg Eqs(i) and (ii) , we get

  l=1 and m=-1

l2+m2=2