document.write( "Question 87297: Given a line containing the points (1,4),(2,7),and(3,10) determine the slope-intercept form of the equation, provide one additional point on this line, and graph the function. \n" ); document.write( "
Algebra.Com's Answer #63237 by jim_thompson5910(35256)\"\" \"About 
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Lets find the equation of the line through the two points (1,4) and (3,10)\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 (\"3\",\"10\")
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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 (\"3\",\"10\"))
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\n" ); document.write( " \"m=%2810-4%29%2F%283-1%29\" Plug in \"y%5B2%5D=10\",\"y%5B1%5D=4\",\"x%5B2%5D=3\",\"x%5B1%5D=1\" (these are the coordinates of given points)
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\n" ); document.write( " \"m=+6%2F2\" Subtract the terms in the numerator \"10-4\" to get \"6\". Subtract the terms in the denominator \"3-1\" to get \"2\"
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\n" ); document.write( " \"m=3\" Reduce
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\n" ); document.write( " So the slope is
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\n" ); document.write( " \"m=3\"
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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=%283%29%28x-1%29\" Plug in \"m=3\", \"x%5B1%5D=1\", and \"y%5B1%5D=4\" (these values are given)
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\n" ); document.write( " \"y-4=3x%2B%283%29%28-1%29\" Distribute \"3\"
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\n" ); document.write( " \"y-4=3x-3\" Multiply \"3\" and \"-1\" to get \"-3%2F1\". Now reduce \"-3%2F1\" to get \"-3\"
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\n" ); document.write( " \"y=3x-3%2B4\" Add \"4\" to both sides to isolate y
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\n" ); document.write( " \"y=3x%2B1\" Combine like terms \"-3\" and \"4\" to get \"1\"
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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 (\"3\",\"10\") is:\"y=3x%2B1\"
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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\" and the y-intercept is \"b=1\"
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\n" ); document.write( " Notice if we graph the equation \"y=3x%2B1\" and plot the points (\"1\",\"4\") and (\"3\",\"10\"), we get this: (note: if you need help with graphing, check out this solver)
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\n" ); document.write( " Graph of \"y=3x%2B1\" through the points (\"1\",\"4\") and (\"3\",\"10\")
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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( "Now lets plot the point (2,7) and \"y=3x%2B1\"\r
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\n" ); document.write( "\n" ); document.write( " graph of \"y=3x%2B1\" with the point (2,7)\r
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\n" ); document.write( "\n" ); document.write( "Since the point is on the line, the equation of the line that goes through (1,4),(2,7),and(3,10) is \"y=3x%2B1\"\r
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\n" ); document.write( "\n" ); document.write( "Now lets pick any other x value so we can plot another point. Let x=0\r
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\n" ); document.write( "\n" ); document.write( "\"3%280%29%2B1=0%2B1=1\" plug in \"x=0\"\r
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\n" ); document.write( "\n" ); document.write( "So we have another point (0,1)\r
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\n" ); document.write( "\n" ); document.write( "So we have this graph and these points\r
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\n" ); document.write( "\n" ); document.write( " graph of \"y=3x%2B1\" with the points (0,1),(1,4),(2,7), and (3,10)
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