$\"\"$

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The function is $\"\"$

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$\"\"$ (Apply the derivative with respect to x)

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$\"\"$ (The derivative sum and difference rule)

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$\"\"$ (The derivative power rule)

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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The equation passes to the point (0, 4)

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So, slope $\"\"$

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$\"\"$ (Substitute x = 0)

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$\"\"$

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The point-slope form is $\"\"$

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

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$\"\"$

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$\"\"$

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$\"\"$

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Therefore the tangent line is $\"\"$ .