$\"\"$

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Observe the table :

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Formula for rate of change: $\"\"$ .

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Substitute $\"\"$ and $\"\"$ in rate of change formula.

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$\"\"$

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$\"\"$

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$\"\"$

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The rate of change is $\"\"$ .

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$\"\"$

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Substitute $\"\"$ and $\"\"$ in rate of change formula.

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$\"\"$

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$\"\"$

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The rate of change is $\"\"$ .

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Substitute $\"\"$ and $\"\"$ in rate of change formula.

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$\"\"$

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$\"\"$

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$\"\"$

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The rate of change is $\"\"$ .

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$\"\"$

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Substitute $\"\"$ and $\"\"$ in rate of change formula.

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$\"\"$

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$\"\"$

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The rate of change is $\"\"$ .

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The rate of change is not constant.

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Thus, the function is Non-linear.

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$\"\"$

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No ; the $\"\"$ values do not increase at a constant rate.