$\"\"$

The quadratic function represents parabola of a graph.

The quadratic function $\"\"$ .

Compare with the standard form of quadratic function $\"\"$ .

$\"\"$ .

Since $\"\"$ ,the parabola opens downwards and has its maximum value.

$\"\"$

Maximum value of a quadratic function is vertex $\"\"$ .

$\"\"$ .

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Maximum points are $\"\"$ = $\"\"$

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Maximum value of the function is $\"\"$ .