document.write( "Question 102872: What is the equation in slope intercept form for the line through each pair of points?\r
\n" ); document.write( "\n" ); document.write( "(-3,1) and (2,4)\r
\n" ); document.write( "\n" ); document.write( "I think the slope is 3/5... so I'm thinking it's y=3/5x + some number... but I'm having problems getting the rest. Help would be much appreciated.
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Algebra.Com's Answer #74818 by edjones(8007)\"\" \"About 
You can put this solution on YOUR website!
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Solved by pluggable solver: Finding the Equation of a Line
First lets find the slope through the points (\"-3\",\"1\") and (\"2\",\"4\")
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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 (\"-3\",\"1\") and (\"x%5B2%5D\",\"y%5B2%5D\") is the second point (\"2\",\"4\"))
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\n" ); document.write( " \"m=%284-1%29%2F%282--3%29\" Plug in \"y%5B2%5D=4\",\"y%5B1%5D=1\",\"x%5B2%5D=2\",\"x%5B1%5D=-3\" (these are the coordinates of given points)
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\n" ); document.write( " \"m=+3%2F5\" Subtract the terms in the numerator \"4-1\" to get \"3\". Subtract the terms in the denominator \"2--3\" to get \"5\"
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\n" ); document.write( " So the slope is
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\n" ); document.write( " \"m=3%2F5\"
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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-1=%283%2F5%29%28x--3%29\" Plug in \"m=3%2F5\", \"x%5B1%5D=-3\", and \"y%5B1%5D=1\" (these values are given)
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\n" ); document.write( " \"y-1=%283%2F5%29%28x%2B3%29\" Rewrite \"x--3\" as \"x%2B3\"
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\n" ); document.write( " \"y-1=%283%2F5%29x%2B%283%2F5%29%283%29\" Distribute \"3%2F5\"
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\n" ); document.write( " \"y-1=%283%2F5%29x%2B9%2F5\" Multiply \"3%2F5\" and \"3\" to get \"9%2F5\"
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\n" ); document.write( " \"y=%283%2F5%29x%2B9%2F5%2B1\" Add \"1\" to both sides to isolate y
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\n" ); document.write( " \"y=%283%2F5%29x%2B14%2F5\" Combine like terms \"9%2F5\" and \"1\" to get \"14%2F5\" (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 (\"-3\",\"1\") and (\"2\",\"4\") is:\"y=%283%2F5%29x%2B14%2F5\"
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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=3%2F5\" and the y-intercept is \"b=14%2F5\"
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\n" ); document.write( " Notice if we graph the equation \"y=%283%2F5%29x%2B14%2F5\" and plot the points (\"-3\",\"1\") and (\"2\",\"4\"), we get this: (note: if you need help with graphing, check out this solver)
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\n" ); document.write( " Graph of \"y=%283%2F5%29x%2B14%2F5\" through the points (\"-3\",\"1\") and (\"2\",\"4\")
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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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