$\"\"$

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(a)

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The growth rate is $\"\"$ , where $\"\"$ is the time in years and $\"\"$ is the height in centimeters.

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$\"\"$

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$\"\"$

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Apply integral on each side.

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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The height after $\"\"$ years is $\"\"$ .

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When $\"\"$ , the seedlings height is $\"\"$ cm.

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$\"\"$ .

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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Substitute $\"\"$ .

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$\"\"$ .

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Substitute $\"\"$ in $\"\"$ .

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The height after $\"\"$ years is $\"\"$ .

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$\"\"$

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(b)

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Find how tall the shrubs when they are sold.

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The shrubs are sold after $\"\"$ years.

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Therefore, $\"\"$ .

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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$\"\"$

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The height of shrubs when they are sold is $\"\"$ cm.

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$\"\"$

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(a) The height after $\"\"$ years is $\"\"$ .

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(b) The height of shrub after sold is $\"\"$ cm.