document.write( "Question 101532: write an equation of the line passing through (-3,8) (5,4) \n" ); document.write( "
Algebra.Com's Answer #73914 by jim_thompson5910(35256)\"\" \"About 
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Solved by pluggable solver: Finding the Equation of a Line
First lets find the slope through the points (\"-3\",\"8\") and (\"5\",\"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\",\"8\") and (\"x%5B2%5D\",\"y%5B2%5D\") is the second point (\"5\",\"4\"))
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\n" ); document.write( " \"m=%284-8%29%2F%285--3%29\" Plug in \"y%5B2%5D=4\",\"y%5B1%5D=8\",\"x%5B2%5D=5\",\"x%5B1%5D=-3\" (these are the coordinates of given points)
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\n" ); document.write( " \"m=+-4%2F8\" Subtract the terms in the numerator \"4-8\" to get \"-4\". Subtract the terms in the denominator \"5--3\" to get \"8\"
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\n" ); document.write( " \"m=-1%2F2\" Reduce
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\n" ); document.write( " So the slope is
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\n" ); document.write( " \"m=-1%2F2\"
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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=%28-1%2F2%29%28x--3%29\" Plug in \"m=-1%2F2\", \"x%5B1%5D=-3\", and \"y%5B1%5D=8\" (these values are given)
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\n" ); document.write( " \"y-8=%28-1%2F2%29%28x%2B3%29\" Rewrite \"x--3\" as \"x%2B3\"
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\n" ); document.write( " \"y-8=%28-1%2F2%29x%2B%28-1%2F2%29%283%29\" Distribute \"-1%2F2\"
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\n" ); document.write( " \"y-8=%28-1%2F2%29x-3%2F2\" Multiply \"-1%2F2\" and \"3\" to get \"-3%2F2\"
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\n" ); document.write( " \"y=%28-1%2F2%29x-3%2F2%2B8\" Add \"8\" to both sides to isolate y
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\n" ); document.write( " \"y=%28-1%2F2%29x%2B13%2F2\" Combine like terms \"-3%2F2\" and \"8\" to get \"13%2F2\" (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\",\"8\") and (\"5\",\"4\") is:\"y=%28-1%2F2%29x%2B13%2F2\"
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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=-1%2F2\" and the y-intercept is \"b=13%2F2\"
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\n" ); document.write( " Notice if we graph the equation \"y=%28-1%2F2%29x%2B13%2F2\" and plot the points (\"-3\",\"8\") and (\"5\",\"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=%28-1%2F2%29x%2B13%2F2\" through the points (\"-3\",\"8\") and (\"5\",\"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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