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The demand equation is $\"\"$ .

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Where,

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$\"\"$ is the price in dollars.

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$\"\"$ is the quantity sold of a certain product .

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Solve $\"\"$ for $\"\"$ .

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$\"\"$ .

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(a)

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The revenue $\"\"$ .

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

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$\"\"$

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Revenue $\"\"$ .

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(b)

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The quantity sold of a certain product $\"\"$ .

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Revenue $\"\"$ .

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$\"\"$

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The revenue if 20 units are sold is $ $\"\"$ .

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(c)

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The function $\"\"$ is a quadratic function.

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Compare the function with standard form of a quadratic function.

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$\"\"$ .

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Since $\"\"$ , the vertex has the maximum point on the parabola.

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The revenue $\"\"$ is a maximum when the quantity sold of a certain product $\"\"$ is $\"\"$ .

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$\"\"$

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Maximum revenue :

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$\"\"$

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Maximum revenue is $ $\"\"$ .

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(d)

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The price $\"\"$ .

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Maximum revenue is $ $\"\"$ at $\"\"$ .

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At $\"\"$ , the company charge to maximum price.

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The maximum price :

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$\"\"$

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$ $\"\"$ should the company charge to maximize the revenue.

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(e)

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Graph $\"\"$ and $\"\"$ are on the same Cartesian plane.

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Find where the graphs intersects.

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$\"\"$

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The graph is shown below :

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$\"\"$

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The graphs intersect at $\"\"$ and $\"\"$ .

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From the graph the company should charge between $ $\"\"$ and $ $\"\"$ to earn at least $ $\"\"$ . in revenue.

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(a) Revenue $\"\"$ .

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(b)The revenue if 20 units are sold is $ $\"\"$ .

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(c) The maximum quantity is $\"\"$ and Maximum revenue is $ $\"\"$ .

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(d) $ $\"\"$ should the company charge to maximize the revenue.

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(e) The company should charge between $ $\"\"$ and $ $\"\"$ to earn at least $ $\"\"$ in revenue.