document.write( "Question 954301: Find an equation of the line that passes through the points (-1, -2) and (4, -5) \n" ); document.write( "
Algebra.Com's Answer #582822 by MathLover1(20849)\"\" \"About 
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Solved by pluggable solver: Finding the Equation of a Line
First lets find the slope through the points (\"-1\",\"-2\") and (\"4\",\"-5\")
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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\",\"-2\") and (\"x%5B2%5D\",\"y%5B2%5D\") is the second point (\"4\",\"-5\"))
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\n" ); document.write( " \"m=%28-5--2%29%2F%284--1%29\" Plug in \"y%5B2%5D=-5\",\"y%5B1%5D=-2\",\"x%5B2%5D=4\",\"x%5B1%5D=-1\" (these are the coordinates of given points)
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\n" ); document.write( " \"m=+-3%2F5\" Subtract the terms in the numerator \"-5--2\" to get \"-3\". Subtract the terms in the denominator \"4--1\" 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--2=%28-3%2F5%29%28x--1%29\" Plug in \"m=-3%2F5\", \"x%5B1%5D=-1\", and \"y%5B1%5D=-2\" (these values are given)
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\n" ); document.write( " \"y%2B2=%28-3%2F5%29%28x--1%29\" Rewrite \"y--2\" as \"y%2B2\"
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\n" ); document.write( " \"y%2B2=%28-3%2F5%29%28x%2B1%29\" Rewrite \"x--1\" as \"x%2B1\"
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\n" ); document.write( " \"y%2B2=%28-3%2F5%29x%2B%28-3%2F5%29%281%29\" Distribute \"-3%2F5\"
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\n" ); document.write( " \"y%2B2=%28-3%2F5%29x-3%2F5\" Multiply \"-3%2F5\" and \"1\" to get \"-3%2F5\"
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\n" ); document.write( " \"y=%28-3%2F5%29x-3%2F5-2\" Subtract \"2\" from both sides to isolate y
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\n" ); document.write( " \"y=%28-3%2F5%29x-13%2F5\" Combine like terms \"-3%2F5\" and \"-2\" to get \"-13%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 (\"-1\",\"-2\") and (\"4\",\"-5\") is:\"y=%28-3%2F5%29x-13%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=-13%2F5\"
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\n" ); document.write( " Notice if we graph the equation \"y=%28-3%2F5%29x-13%2F5\" and plot the points (\"-1\",\"-2\") and (\"4\",\"-5\"), we get this: (note: if you need help with graphing, check out this solver)
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\n" ); document.write( " Graph of \"y=%28-3%2F5%29x-13%2F5\" through the points (\"-1\",\"-2\") and (\"4\",\"-5\")
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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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