document.write( "Question 114186: Write the equation of the line that passes through point (7, –18) with a slope of –2. \n" ); document.write( "
Algebra.Com's Answer #83089 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "If you want to find the equation of line with a given a slope of \"-2\" which goes through the point (\"7\",\"-18\"), you can simply use the point-slope formula to find the equation:\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 the given point\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--18=%28-2%29%28x-7%29\" Plug in \"m=-2\", \"x%5B1%5D=7\", and \"y%5B1%5D=-18\" (these values are given)\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B18=%28-2%29%28x-7%29\" Rewrite \"y--18\" as \"y%2B18\"\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B18=-2x%2B%28-2%29%28-7%29\" Distribute \"-2\"\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B18=-2x%2B14\" Multiply \"-2\" and \"-7\" to get \"14\"\r
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\n" ); document.write( "\n" ); document.write( "\"y=-2x%2B14-18\" Subtract 18 from both sides to isolate y\r
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\n" ); document.write( "\n" ); document.write( "\"y=-2x-4\" Combine like terms \"14\" and \"-18\" to get \"-4\" \r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
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\n" ); document.write( "\n" ); document.write( "So the equation of the line with a slope of \"-2\" which goes through the point (\"7\",\"-18\") is:\r
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\n" ); document.write( "\n" ); document.write( "\"y=-2x-4\" which is now in \"y=mx%2Bb\" form where the slope is \"m=-2\" and the y-intercept is \"b=-4\"\r
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\n" ); document.write( "\n" ); document.write( "Notice if we graph the equation \"y=-2x-4\" and plot the point (\"7\",\"-18\"), we get (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=-2x-4\" through the point (\"7\",\"-18\")\r
\n" ); document.write( "\n" ); document.write( "and we can see that the point lies on the line. Since we know the equation has a slope of \"-2\" and goes through the point (\"7\",\"-18\"), this verifies our answer.
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