\"\"

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The line equation in slope-intercept form is \"\",

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where m is the slope and b is the y-intercept.

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Write the two functions as co-ordinates

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\"\" as \"\"

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\"\" as \"\"

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\"\"

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First find the slope

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m = \"\"

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    = \"\"                   (Substitute \"\" and \"\")

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    = \"\"                          (Subtract:\"\")­­

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    = -2.                              (Divide:\"\")­­

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\"\"

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The line crosses the y-axis at (0, 21). So the y-intercept is 21.

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Substitute \"\"and \"\" in slope-intercept form line equation.

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\"\"                            \ \

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\"\"

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The function is \"\".