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NDA2015MathematicsThree Dimensional GeometryActual

The radius of the sphere 3 x^2+3 y^2+3 z^2-8 x+4 y+8 z-15=0 is

Options

  1. A2
  2. B3
  3. C4
  4. D5

Correct answer

B. 3

Step-by-step solution

aligned & 3 x^2+3 y^2+3 z^2-8 y+4 y+8 z-15=0 & x^2+y^2+z^2- 8 3 x+ 4 3 y+ 8 3 z-5=0 & (x- 4 3 )^2- 16 9 + (y+ 2 3 )^2- 4 9 + (z+ 4 3 )^2- 16 9 -5=0 & (x- 4 3 )^2+ (y+ 2 3 )^2+ (z+ 4 3 )^2=(3)^2 aligned So radius is 3 .

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