$\"\"$

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The functions are $\"\"$ .

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a) (f + g)(x)

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$\"open$

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$\"\"$ (Substitute $\"\"$ )

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

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b) (f $\"\"$ g)(x)

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$\"open$

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$\"\"$ (Substitute $\"\"$ )

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

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c) $\"open$

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$\"open$

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$

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$\"\"$

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

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d) $\"open$

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$\"open$

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$\"\"$ (Substitute $\"\"$ ) $\"\"$

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(f + g)(x) $\"\"$ , (f $\"\"$ g)(x) $\"\"$ , $\"open$ $\"\"$ and $\"open$ $\"\"$ .