$\"\"$

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The vectors are $\"\"$ , $\"\"$ and $\"\"$ .

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The vector equation is $\"\"$ .

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$\"\"$

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$\"\"$

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Substitute $\"\"$ , $\"\"$ and $\"\"$ .

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$\"\"$ .

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$\"\"$

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$\"\"$

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Since $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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Therefore, the equation represents a sphere with center $\"\"$ and radius $\"\"$ .

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$\"\"$

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The equation represents a sphere with center $\"\"$ and radius $\"\"$ .