document.write( "Question 462594: Find the general form of the equation of the line that passes through the points (-1,-2) and (7,1). \n" ); document.write( "
Algebra.Com's Answer #317088 by MathLover1(20849)\"\" \"About 
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Solved by pluggable solver: Finding the Equation of a Line
First lets find the slope through the points (\"-1\",\"-2\") and (\"7\",\"1\")
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\n" ); document.write( " \"m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29\" Start with the slope formula (note: (\"x%5B1%5D\",\"y%5B1%5D\") is the first point (\"-1\",\"-2\") and (\"x%5B2%5D\",\"y%5B2%5D\") is the second point (\"7\",\"1\"))
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\n" ); document.write( " \"m=%281--2%29%2F%287--1%29\" Plug in \"y%5B2%5D=1\",\"y%5B1%5D=-2\",\"x%5B2%5D=7\",\"x%5B1%5D=-1\" (these are the coordinates of given points)
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\n" ); document.write( " \"m=+3%2F8\" Subtract the terms in the numerator \"1--2\" to get \"3\". Subtract the terms in the denominator \"7--1\" to get \"8\"
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\n" ); document.write( " So the slope is
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\n" ); document.write( " \"m=3%2F8\"
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\n" ); document.write( "Now let's use the point-slope formula to find the equation of the line:
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\n" ); document.write( " ------Point-Slope Formula------
\n" ); document.write( " \"y-y%5B1%5D=m%28x-x%5B1%5D%29\" where \"m\" is the slope, and (\"x%5B1%5D\",\"y%5B1%5D\") is one of the given points
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\n" ); document.write( " So lets use the Point-Slope Formula to find the equation of the line
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\n" ); document.write( " \"y--2=%283%2F8%29%28x--1%29\" Plug in \"m=3%2F8\", \"x%5B1%5D=-1\", and \"y%5B1%5D=-2\" (these values are given)
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\n" ); document.write( " \"y%2B2=%283%2F8%29%28x--1%29\" Rewrite \"y--2\" as \"y%2B2\"
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\n" ); document.write( " \"y%2B2=%283%2F8%29%28x%2B1%29\" Rewrite \"x--1\" as \"x%2B1\"
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\n" ); document.write( " \"y%2B2=%283%2F8%29x%2B%283%2F8%29%281%29\" Distribute \"3%2F8\"
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\n" ); document.write( " \"y%2B2=%283%2F8%29x%2B3%2F8\" Multiply \"3%2F8\" and \"1\" to get \"3%2F8\"
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\n" ); document.write( " \"y=%283%2F8%29x%2B3%2F8-2\" Subtract \"2\" from both sides to isolate y
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\n" ); document.write( " \"y=%283%2F8%29x-13%2F8\" Combine like terms \"3%2F8\" and \"-2\" to get \"-13%2F8\" (note: if you need help with combining fractions, check out this solver)
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\n" ); document.write( " Answer:
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\n" ); document.write( " So the equation of the line which goes through the points (\"-1\",\"-2\") and (\"7\",\"1\") is:\"y=%283%2F8%29x-13%2F8\"
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\n" ); document.write( " The equation is now in \"y=mx%2Bb\" form (which is slope-intercept form) where the slope is \"m=3%2F8\" and the y-intercept is \"b=-13%2F8\"
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\n" ); document.write( " Notice if we graph the equation \"y=%283%2F8%29x-13%2F8\" and plot the points (\"-1\",\"-2\") and (\"7\",\"1\"), we get this: (note: if you need help with graphing, check out this solver)
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\n" ); document.write( " Graph of \"y=%283%2F8%29x-13%2F8\" through the points (\"-1\",\"-2\") and (\"7\",\"1\")
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\n" ); document.write( " Notice how the two points lie on the line. This graphically verifies our answer.
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\n" ); document.write( "\n" ); document.write( "so, your line in \"slope-intercept\" form is: \"y=%283%2F8%29x-13%2F8\"\r
\n" ); document.write( "\n" ); document.write( "in the general form of the equation of the line \"ax+%2B+by+=+c\" will be:\r
\n" ); document.write( "\n" ); document.write( "\"%283%2F8%29x+%2B+y=-13%2F8\"
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