document.write( "Question 954280: Find an equation of the line passing through the origin and parallel to the line passing through the points (2,8) and (4,12). \n" ); document.write( "
Algebra.Com's Answer #582820 by MathLover1(20850)\"\" \"About 
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first,the equation of the line passing through the points (2,8) and (4,12)\r
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Solved by pluggable solver: Finding the Equation of a Line
First lets find the slope through the points (\"2\",\"8\") and (\"4\",\"12\")
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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 (\"2\",\"8\") and (\"x%5B2%5D\",\"y%5B2%5D\") is the second point (\"4\",\"12\"))
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\n" ); document.write( " \"m=%2812-8%29%2F%284-2%29\" Plug in \"y%5B2%5D=12\",\"y%5B1%5D=8\",\"x%5B2%5D=4\",\"x%5B1%5D=2\" (these are the coordinates of given points)
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\n" ); document.write( " \"m=+4%2F2\" Subtract the terms in the numerator \"12-8\" to get \"4\". Subtract the terms in the denominator \"4-2\" to get \"2\"
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\n" ); document.write( " \"m=2\" Reduce
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\n" ); document.write( " So the slope is
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\n" ); document.write( " \"m=2\"
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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-8=%282%29%28x-2%29\" Plug in \"m=2\", \"x%5B1%5D=2\", and \"y%5B1%5D=8\" (these values are given)
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\n" ); document.write( " \"y-8=2x%2B%282%29%28-2%29\" Distribute \"2\"
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\n" ); document.write( " \"y-8=2x-4\" Multiply \"2\" and \"-2\" to get \"-4%2F1\". Now reduce \"-4%2F1\" to get \"-4\"
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\n" ); document.write( " \"y=2x-4%2B8\" Add \"8\" to both sides to isolate y
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\n" ); document.write( " \"y=2x%2B4\" Combine like terms \"-4\" and \"8\" to get \"4\"
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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 (\"2\",\"8\") and (\"4\",\"12\") is:\"y=2x%2B4\"
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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=2\" and the y-intercept is \"b=4\"
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\n" ); document.write( " Notice if we graph the equation \"y=2x%2B4\" and plot the points (\"2\",\"8\") and (\"4\",\"12\"), we get this: (note: if you need help with graphing, check out this solver)
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\n" ); document.write( " Graph of \"y=2x%2B4\" through the points (\"2\",\"8\") and (\"4\",\"12\")
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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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\n" ); document.write( "\n" ); document.write( "then, the line \"y=mx%2Bb\" parallel to line \"y=2x%2B4\" will have same slope \"m=2\" and since passing through origin (\"0\",\"0\", y-intercept \"b=0\"\r
\n" ); document.write( "\n" ); document.write( "so, equation of the line parallel to line \"y=2x%2B4\" is \"y=2x\"\r
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