document.write( "Question 87742: ok I suck at math and I need help with some homework. The main topic is finding the equation of a line using two points or a point and slope. I can give two examples of these questions. one is this way:\r
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Algebra.Com's Answer #63667 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( "If you want to find the equation of line with a given a slope of \"2\" which goes through the point (\"1\",\"-2\"), 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 (\"x%5B1%5D\",\"y%5B1%5D\") 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--2=%282%29%28x-1%29\" Plug in \"m=2\", \"x%5B1%5D=1\", and \"y%5B1%5D=-2\" (these values are given)\r
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\n" ); document.write( "\n" ); document.write( "\"y--2=%282%29x-%282%29%281%29%29\" Distribute \"2\"\r
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\n" ); document.write( "\n" ); document.write( "\"y--2=%282%29x%2B%28-2%29%281%29%29\" Multiply the negatives\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B2=%282%29x%2B-2\" Multiply \"-2\" and \"1\" to get \"-2\"\r
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\n" ); document.write( "\n" ); document.write( "\"y=%282%29x%2B-2%2B-2\"Subtract \"-2\" from both sides\r
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\n" ); document.write( "\n" ); document.write( "\"y=%282%29x%2B-4\" Combine like terms\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 (\"1\",\"-2\") is:\r
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\n" ); document.write( "\n" ); document.write( "\"y=%282%29x%2B-4\" which is now in \"y=mx%2Bb\" form where the slope is \"m=2\" (so this shows our equation has a slope of \"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=%282%29x%2B-4\" (note: if you need help with graphing, check out this solver) and plot the point (\"1\",\"-2\"), we get\r
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\n" ); document.write( "\n" ); document.write( " Graph of \"y=%282%29x%2B-4\" through the point (\"1\",\"-2\")\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 (\"1\",\"-2\"), this verifies our answer.\r
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Solved by pluggable solver: Finding the Equation of a Line
First lets find the slope through the points (\"-1\",\"4\") and (\"2\",\"-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\",\"4\") and (\"x%5B2%5D\",\"y%5B2%5D\") is the second point (\"2\",\"-1\"))
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\n" ); document.write( " \"m=%28-1-4%29%2F%282--1%29\" Plug in \"y%5B2%5D=-1\",\"y%5B1%5D=4\",\"x%5B2%5D=2\",\"x%5B1%5D=-1\" (these are the coordinates of given points)
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\n" ); document.write( " \"m=+-5%2F3\" Subtract the terms in the numerator \"-1-4\" to get \"-5\". Subtract the terms in the denominator \"2--1\" to get \"3\"
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\n" ); document.write( " So the slope is
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\n" ); document.write( " \"m=-5%2F3\"
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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-4=%28-5%2F3%29%28x--1%29\" Plug in \"m=-5%2F3\", \"x%5B1%5D=-1\", and \"y%5B1%5D=4\" (these values are given)
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\n" ); document.write( " \"y-4=%28-5%2F3%29%28x%2B1%29\" Rewrite \"x--1\" as \"x%2B1\"
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\n" ); document.write( " \"y-4=%28-5%2F3%29x%2B%28-5%2F3%29%281%29\" Distribute \"-5%2F3\"
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\n" ); document.write( " \"y-4=%28-5%2F3%29x-5%2F3\" Multiply \"-5%2F3\" and \"1\" to get \"-5%2F3\"
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\n" ); document.write( " \"y=%28-5%2F3%29x-5%2F3%2B4\" Add \"4\" to both sides to isolate y
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\n" ); document.write( " \"y=%28-5%2F3%29x%2B7%2F3\" Combine like terms \"-5%2F3\" and \"4\" to get \"7%2F3\" (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\",\"4\") and (\"2\",\"-1\") is:\"y=%28-5%2F3%29x%2B7%2F3\"
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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=-5%2F3\" and the y-intercept is \"b=7%2F3\"
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\n" ); document.write( " Notice if we graph the equation \"y=%28-5%2F3%29x%2B7%2F3\" and plot the points (\"-1\",\"4\") and (\"2\",\"-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=%28-5%2F3%29x%2B7%2F3\" through the points (\"-1\",\"4\") and (\"2\",\"-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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