$\"\"$

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The distance function is $\"\"$

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(a).

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At what time $\"\"$ will ball strike the ground.

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Therefore ball will strike the ground at distance $\"\"$ .

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

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ or $\"\"$ .

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The ball will strike the ground at time $\"\"$ is $\"\"$ .

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$\"\"$

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(b).

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The distance from the ground and ball is $\"\"$ .

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Therefore substitute $\"\"$ in $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ and $\"\"$

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$\"\"$ and $\"\"$

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The $\"\"$ -intercepts are $\"\"$ or $\"\"$ .

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Find the $\"\"$ -intercept by substituting $\"\"$ in $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$ -intercept is $\"\"$ .

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$\"\"$

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Find the vertex of above quadratic function $\"\"$ .

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$\"\"$

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Compare it to $\"\"$ .

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

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Since $\"\"$ , then the parabola open upward.

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$\"\"$

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$\"\"$

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$\"\"$ coordinate of vertex is $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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Vertex $\"\"$

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$\"\"$

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Graph the quadratic equation $\"\"$ .

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Draw the coordinate plane.

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Plot the intercepts and vertex.

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Connect the plotted points.

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$\"\"$

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Therfore the time $\"\"$ is in between $\"\"$ and $\"\"$ .

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Hence $\"\"$

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$\"\"$

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(a). $\"\"$ .

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(b). $\"\"$ .