document.write( "Question 118099: write an equation of the line that passes through (4,3) and (2,-2) \n" ); document.write( "
Algebra.Com's Answer #86175 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
First lets find the slope through the points (\"4\",\"3\") and (\"2\",\"-2\")\r
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\n" ); document.write( "\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: is the first point (\"4\",\"3\") and is the second point (\"2\",\"-2\"))\r
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\n" ); document.write( "\n" ); document.write( "\"m=%28-2-3%29%2F%282-4%29\" Plug in \"y%5B2%5D=-2\",\"y%5B1%5D=3\",\"x%5B2%5D=2\",\"x%5B1%5D=4\" (these are the coordinates of given points)\r
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\n" ); document.write( "\n" ); document.write( "\"m=+-5%2F-2\" Subtract the terms in the numerator \"-2-3\" to get \"-5\". Subtract the terms in the denominator \"2-4\" to get \"-2\"\r
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\n" ); document.write( "\n" ); document.write( "\"m=5%2F2\" Reduce\r
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\n" ); document.write( "\n" ); document.write( "So the slope is\r
\n" ); document.write( "\n" ); document.write( "\"m=5%2F2\"\r
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\n" ); document.write( "\n" ); document.write( "Now let's use the point-slope formula to find the equation of the line:\r
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\n" ); document.write( "\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 is one of the given points\r
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\n" ); document.write( "\n" ); document.write( "So lets use the Point-Slope Formula to find the equation of the line\r
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\n" ); document.write( "\n" ); document.write( "\"y-3=%285%2F2%29%28x-4%29\" Plug in \"m=5%2F2\", \"x%5B1%5D=4\", and \"y%5B1%5D=3\" (these values are given)\r
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\n" ); document.write( "\n" ); document.write( "\"y-3=%285%2F2%29x%2B%285%2F2%29%28-4%29\" Distribute \"5%2F2\"\r
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\n" ); document.write( "\n" ); document.write( "\"y-3=%285%2F2%29x-10\" Multiply \"5%2F2\" and \"-4\" to get \"-20%2F2\". Now reduce \"-20%2F2\" to get \"-10\"\r
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\n" ); document.write( "\n" ); document.write( "\"y=%285%2F2%29x-10%2B3\" Add \"3\" to both sides to isolate y\r
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\n" ); document.write( "\n" ); document.write( "\"y=%285%2F2%29x-7\" Combine like terms \"-10\" and \"3\" to get \"-7\" \r
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\n" ); document.write( "\n" ); document.write( "So the equation of the line which goes through the points (\"4\",\"3\") and (\"2\",\"-2\") is:\"y=%285%2F2%29x-7\"\r
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\n" ); document.write( "\n" ); document.write( "The equation is now in \"y=mx%2Bb\" form (which is slope-intercept form) where the slope is \"m=5%2F2\" and the y-intercept is \"b=-7\"\r
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\n" ); document.write( "\n" ); document.write( "Notice if we graph the equation \"y=%285%2F2%29x-7\" and plot the points (\"4\",\"3\") and (\"2\",\"-2\"), we get this: (note: if you need help with graphing, check out this solver)\r
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\n" ); document.write( "\n" ); document.write( " Graph of \"y=%285%2F2%29x-7\" through the points (\"4\",\"3\") and (\"2\",\"-2\")\r
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\n" ); document.write( "\n" ); document.write( "Notice how the two points lie on the line. This graphically verifies our answer.
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