\"\"

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Slope of the two non vertical lines is \"\".

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The x-coordinate are same. So, the line is x = 4. The line is vertical line.

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So, slope is undefined.\"\"

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Check the solution by substituting the values.

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Replace \"\" in slope formula.

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\"\"

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\"\"                             (Subtract: \"\")

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\"\"                                 (Subtract: \"\")

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\"\"                                  (Divide: \"\")

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Slope is undefined.\"\"

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Slope is undefined.