document.write( "Question 110759: WRite the equation of the line passing through (4,-25) and (-3, 17).\r
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Algebra.Com's Answer #80719 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
First lets find the slope through the points (\"4\",\"-25\") and (\"-3\",\"17\")\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\",\"-25\") and is the second point (\"-3\",\"17\"))\r
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\n" ); document.write( "\n" ); document.write( "\"m=%2817--25%29%2F%28-3-4%29\" Plug in \"y%5B2%5D=17\",\"y%5B1%5D=-25\",\"x%5B2%5D=-3\",\"x%5B1%5D=4\" (these are the coordinates of given points)\r
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\n" ); document.write( "\n" ); document.write( "\"m=+42%2F-7\" Subtract the terms in the numerator \"17--25\" to get \"42\". Subtract the terms in the denominator \"-3-4\" to get \"-7\"\r
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\n" ); document.write( "\n" ); document.write( "\"m=-6\" Reduce\r
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\n" ); document.write( "\n" ); document.write( "So the slope is\r
\n" ); document.write( "\n" ); document.write( "\"m=-6\"\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--25=%28-6%29%28x-4%29\" Plug in \"m=-6\", \"x%5B1%5D=4\", and \"y%5B1%5D=-25\" (these values are given)\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B25=%28-6%29%28x-4%29\" Rewrite \"y--25\" as \"y%2B25\"\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B25=-6x%2B%28-6%29%28-4%29\" Distribute \"-6\"\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B25=-6x%2B24\" Multiply \"-6\" and \"-4\" to get \"24\"\r
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\n" ); document.write( "\n" ); document.write( "\"y=-6x%2B24-25\" Subtract \"25\" from both sides to isolate y\r
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\n" ); document.write( "\n" ); document.write( "\"y=-6x-1\" Combine like terms \"24\" and \"-25\" to get \"-1\" \r
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\n" ); document.write( "\n" ); document.write( "So the equation of the line which goes through the points (\"4\",\"-25\") and (\"-3\",\"17\") is:\"y=-6x-1\"\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=-6\" and the y-intercept is \"b=-1\"\r
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\n" ); document.write( "\n" ); document.write( "Notice if we graph the equation \"y=-6x-1\" and plot the points (\"4\",\"-25\") and (\"-3\",\"17\"), 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=-6x-1\" through the points (\"4\",\"-25\") and (\"-3\",\"17\")\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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