Step 1: \ \

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Observe the graph:

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$\"\"$

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$\"\"$ is defined at $\"\"$ .

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$\"\"$

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$\"\"$ $\"\"$

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$\"\"$

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$\"\"$ is exist. \ \

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$\"\"$

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$\"\"$ fails the continuity test condition (3) at $\"\"$ .

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$\"\"$ is discontinuous at $\"\"$ .

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Step 2:

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Observe the graph:

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$\"\"$

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$\"\"$ is defined at $\"\"$ . \ \ $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ does not exist.

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$\"\"$ fails the continuity test condition (2), (3) at $\"\"$ .

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$\"\"$ is discontinuous at $\"\"$ .

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Step 3:

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Observe the graph:

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$\"\"$ is undefined. \ \ $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ does not exist.

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$\"\"$ fails the continuity test condition (1), (2), (3) at $\"\"$ .

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$\"\"$ is discontinuous at $\"\"$ .

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Solution:

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$\"\"$ is discontinuous at $\"\"$ , $\"\"$ and $\"\"$ . \ \