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1)

 The equation of planes parallel to the plane x+2y+2z+8=0 , which are at a distance of 2 units from the point (1,1,2) are


A) x+2y+2z-5=0 or x+2y+2z-3=0

B) x+2y+2z-6=0 or x+2y+2z-7=0

C) x+2y+2z-13=0 or x+2y+2z-1=0

D) x+2y+2z+3=0 or x+2y+2z-5=0

Answer:

Option C

Explanation:

 Equation  of plane parallel  to the plane

x+2y+2z+8=0 is x+2y+2z+λ=0

 Given distance from the  point (1,1,2)  to the plane.

 x+2y+2z +λ=0 is 2 units

             2=|1+2+4+λ1+4+4|

     ±2=λ+73

λ+7=±6

       λ  = -13,-1

 Hence , equation of plane is

x+2y+2z-13=0 or x+2y+2z-1=0