ISRO Mechanical & Aerospace 2011 - Question 76

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If $v = (x² + y² + z²)^{-1/2}$, then $\sum \partial² v / \partial x²$ is

  • A. -1/2
  • B. -1
  • C. 0
  • D. 1

Answer: C. 0

Explanation: This is the potential function 1/r, which satisfies the Laplace equation $\nabla²(1/r) = 0$.

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