$\"\"$

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The function of the parabola is $\"\"$ .

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The parabola is open downward when the value of $\"\"$ and it has only one $\"\"$ - intecept.

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Consider the function $\"\"$ .

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$\"\"$

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$\"\"$

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The axis of symmetry is $\"\"$ .

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Comapre the equation $\"\"$ with $\"\"$ .

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Therefore $\"\"$ , $\"\"$ and $\"\"$ .

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The general form of vertix is $\"\"$ .

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Substitute $\"\"$ , $\"\"$ and $\"\"$ in the avove equation.

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$\"\"$

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and $\"\"$

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Therefore $\"\"$

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The vertex is $\"\"$ .

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Therefore the function $\"\"$ has only one $\"\"$ -intecept.

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$\"\"$

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The parabola is open downward when the value of $\"\"$ and it has only one $\"\"$ intecept.