document.write( "Question 275270: I have two questions on the equations of lines.\r
\n" ); document.write( "\n" ); document.write( "1)Write an equation of a line passing through the points (-3,5) and (2,-7)\r
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\n" ); document.write( "\n" ); document.write( "2) Write an equation of the line perpendicular to the line 2x-4y=7 and passing through (2,-5)\r
\n" ); document.write( "\n" ); document.write( "I am slightly perplexed, thanks in advance.
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Algebra.Com's Answer #200790 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
# 1\r
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\n" ); document.write( "\n" ); document.write( "First let's find the slope of the line through the points and \r
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\n" ); document.write( "\n" ); document.write( "Note: is the first point . So this means that \"x%5B1%5D=-3\" and \"y%5B1%5D=5\".\r
\n" ); document.write( "\n" ); document.write( "Also, is the second point . So this means that \"x%5B2%5D=2\" and \"y%5B2%5D=-7\".\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.\r
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\n" ); document.write( "\n" ); document.write( "\"m=%28-7-5%29%2F%282--3%29\" Plug in \"y%5B2%5D=-7\", \"y%5B1%5D=5\", \"x%5B2%5D=2\", and \"x%5B1%5D=-3\"\r
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\n" ); document.write( "\n" ); document.write( "\"m=%28-12%29%2F%282--3%29\" Subtract \"5\" from \"-7\" to get \"-12\"\r
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\n" ); document.write( "\n" ); document.write( "\"m=%28-12%29%2F%285%29\" Subtract \"-3\" from \"2\" to get \"5\"\r
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\n" ); document.write( "\n" ); document.write( "So the slope of the line that goes through the points and is \"m=-12%2F5\"\r
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\n" ); document.write( "\n" ); document.write( "Now let's use the point slope formula:\r
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\n" ); document.write( "\n" ); document.write( "\"y-y%5B1%5D=m%28x-x%5B1%5D%29\" Start with the point slope formula\r
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\n" ); document.write( "\n" ); document.write( "\"y-5=%28-12%2F5%29%28x--3%29\" Plug in \"m=-12%2F5\", \"x%5B1%5D=-3\", and \"y%5B1%5D=5\"\r
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\n" ); document.write( "\n" ); document.write( "\"y-5=%28-12%2F5%29%28x%2B3%29\" Rewrite \"x--3\" as \"x%2B3\"\r
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\n" ); document.write( "\n" ); document.write( "\"y-5=%28-12%2F5%29x%2B%28-12%2F5%29%283%29\" Distribute\r
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\n" ); document.write( "\n" ); document.write( "\"y-5=%28-12%2F5%29x-36%2F5\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"y=%28-12%2F5%29x-36%2F5%2B5\" Add 5 to both sides. \r
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\n" ); document.write( "\n" ); document.write( "\"y=%28-12%2F5%29x-11%2F5\" Combine like terms. note: If you need help with fractions, check out this solver.\r
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\n" ); document.write( "\n" ); document.write( "So the equation that goes through the points and is \"y=%28-12%2F5%29x-11%2F5\"\r
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\n" ); document.write( "\n" ); document.write( "# 2\r
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\n" ); document.write( "\n" ); document.write( "\"2x-4y=7\" Start with the given equation.\r
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\n" ); document.write( "\n" ); document.write( "\"-4y=7-2x\" Subtract \"2x\" from both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"-4y=-2x%2B7\" Rearrange the terms.\r
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\n" ); document.write( "\n" ); document.write( "\"y=%28-2x%2B7%29%2F%28-4%29\" Divide both sides by \"-4\" to isolate y.\r
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\n" ); document.write( "\n" ); document.write( "\"y=%28%28-2%29%2F%28-4%29%29x%2B%287%29%2F%28-4%29\" Break up the fraction.\r
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\n" ); document.write( "\n" ); document.write( "\"y=%281%2F2%29x-7%2F4\" Reduce.\r
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\n" ); document.write( "\n" ); document.write( "So the slope of \"y=%281%2F2%29x-7%2F4\" and \"2x-4y=7\" is \"1%2F2\"\r
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Solved by pluggable solver: Finding the Equation of a Line Parallel or Perpendicular to a Given Line

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\n" ); document.write( " Remember, any two perpendicular lines are negative reciprocals of each other. So if you're given the slope of \"1%2F2\", you can find the perpendicular slope by this formula:
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\n" ); document.write( " \"m%5Bp%5D=-1%2Fm\" where \"m%5Bp%5D\" is the perpendicular slope
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\n" ); document.write( " \"m%5Bp%5D=-1%2F%281%2F2%29\" So plug in the given slope to find the perpendicular slope
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\n" ); document.write( " \"m%5Bp%5D=%28-1%2F1%29%282%2F1%29\" When you divide fractions, you multiply the first fraction (which is really \"1%2F1\") by the reciprocal of the second
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\n" ); document.write( " \"m%5Bp%5D=-2%2F1\" Multiply the fractions.
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\n" ); document.write( " So the perpendicular slope is \"-2\"
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\n" ); document.write( " So now we know the slope of the unknown line is \"-2\" (its the negative reciprocal of \"1%2F2\" from the line \"y=%281%2F2%29%2Ax-7%2F4\").\n" ); document.write( "Also since the unknown line goes through (2,-5), we can find the equation by plugging in this info into the point-slope formula
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\n" ); document.write( " Point-Slope Formula:
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\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 the given point
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\n" ); document.write( " \"y%2B5=-2%2A%28x-2%29\" Plug in \"m=-2\", \"x%5B1%5D=2\", and \"y%5B1%5D=-5\"
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\n" ); document.write( " \"y%2B5=-2%2Ax%2B%282%29%282%29\" Distribute \"-2\"
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\n" ); document.write( " \"y%2B5=-2%2Ax%2B4\" Multiply
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\n" ); document.write( " \"y=-2%2Ax%2B4-5\"Subtract \"-5\" from both sides to isolate y
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\n" ); document.write( " \"y=-2%2Ax-1\" Combine like terms
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\n" ); document.write( " So the equation of the line that is perpendicular to \"y=%281%2F2%29%2Ax-7%2F4\" and goes through (\"2\",\"-5\") is \"y=-2%2Ax-1\"
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\n" ); document.write( " So here are the graphs of the equations \"y=%281%2F2%29%2Ax-7%2F4\" and \"y=-2%2Ax-1\"
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\n" ); document.write( " graph of the given equation \"y=%281%2F2%29%2Ax-7%2F4\" (red) and graph of the line \"y=-2%2Ax-1\"(green) that is perpendicular to the given graph and goes through (\"2\",\"-5\")
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