$\"\"$

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The equation is $\"\"$ at the point $\"\"$ .

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The system of equations are $\"\"$ .

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

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$\"\"$

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$\"\"$

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$\"\"$

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The equation is in the form of quadratic equation.

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The general form of quadratic equation is $\"\"$ .

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Here $\"\"$ , $\"\"$ and $\"\"$ .

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There is one solution to the quadratic if the discriminant $\"\"$ equals to $\"\"$ .

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Substitute corresponding values.

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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 tangent line $\"\"$ passes through the point $\"\"$ .

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$\"\"$

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$\"\"$

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

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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

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$\"\"$ .

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

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$\"\"$ .

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Therefore, the line equation is $\"\"$ .

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$\"\"$

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The line equation is $\"\"$ .