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How many lattice points lie on the sphere x^2+y^2+z^2=2013? Information-- [A lattice point has integer coordinates.]

Rushikesh R Jogdand , 12 Years ago
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Askiitians Tutor Team

To determine how many lattice points lie on the sphere defined by the equation \(x^2 + y^2 + z^2 = 2013\), we need to find all integer solutions \((x, y, z)\) that satisfy this equation. A lattice point, as you mentioned, is a point in three-dimensional space where all coordinates are integers.

Understanding the Sphere Equation

The equation \(x^2 + y^2 + z^2 = 2013\) represents a sphere centered at the origin with a radius of \(\sqrt{2013}\). The challenge is to find integer values for \(x\), \(y\), and \(z\) such that their squares add up to 2013.

Finding Integer Solutions

To find the integer solutions, we can start by considering the possible values for \(x\). Since \(x^2\) must be less than or equal to 2013, the maximum value for \(x\) is \(\lfloor \sqrt{2013} \rfloor\), which is approximately 44. Therefore, \(x\) can take values from \(-44\) to \(44\).

  • For each integer value of \(x\), we can compute \(y^2 + z^2 = 2013 - x^2\).
  • This means we need to find pairs of integers \((y, z)\) such that their squares add up to the remaining value.

Iterating Through Possible Values

Let’s break this down step by step:

  1. For each integer \(x\) from \(-44\) to \(44\), calculate \(R = 2013 - x^2\).
  2. Next, we need to find pairs of integers \((y, z)\) such that \(y^2 + z^2 = R\).
  3. For each valid \(y\), \(z\) can be calculated as \(z = \sqrt{R - y^2}\). We need to check if \(z\) is an integer.

Counting the Solutions

To count the total number of lattice points, we can use the symmetry of the sphere. For each unique solution \((x, y, z)\), there are multiple permutations due to the symmetry in the coordinates. Specifically, if all three coordinates are distinct, each solution can be arranged in \(3!\) (6) ways. If two coordinates are the same, it can be arranged in \(3\) ways, and if all three are the same, there is only \(1\) arrangement.

Example Calculation

Let’s consider a specific case. If we set \(x = 0\), we need to solve \(y^2 + z^2 = 2013\). We can iterate through possible values of \(y\) from \(-\sqrt{2013}\) to \(\sqrt{2013}\) and check if \(z^2\) results in a perfect square. This process is repeated for each integer value of \(x\).

Final Thoughts

Finding the exact number of lattice points on the sphere can be computationally intensive, as it involves checking many combinations. However, using programming or systematic counting can yield the total number of solutions efficiently. The final count will depend on how many unique combinations of \((x, y, z)\) satisfy the equation, considering the symmetry of the sphere.

In summary, the task involves iterating through possible integer values for \(x\), calculating the corresponding \(R\), and then finding integer pairs \((y, z)\) that satisfy the equation. The total number of lattice points will be the sum of all valid combinations, adjusted for symmetry.

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