Algebra.Com's Answer #853247 by ikleyn(53419)![\"\"](\"/images/stars/stars-13.gif\")  
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document.write( "which equation represents a line that passes through the points (2,3) and (-1,-3) ?
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document.write( " The solution in the post by @mananth is incorrect: it has many arithmetic errors.\r
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document.write( " I came to bring a correct solution.\r
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document.write( "Having two points given by their coordinates, we first calculate the slope of the line.\r\n" );
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document.write( "To calculate the slope m, use the formula m =  .\r\n" );
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document.write( "The numerator is y2 - y1 = -3 - 3 = -6.\r\n" );
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document.write( "The denominator is x2 - x1 = -1 - 2 = -3.\r\n" );
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document.write( "So, the slope is m =  = 2.\r\n" );
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document.write( "We look for equation in the form \r\n" );
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document.write( " y = mx + b = 2x + b.\r\n" );
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document.write( "We just know the slope 'm'; so, we only need to find 'b'.\r\n" );
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document.write( "To find 'b', plug coordinates (2,3) in this equation\r\n" );
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document.write( " 3 = 2*2 + b\r\n" );
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document.write( "and find b = 3 - 4 = -1.\r\n" );
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document.write( "So the equation of the line is y = 2x - 1. <<<---=== ANSWER\r\n" );
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document.write( "At the end, to be sure, we must check that this equation satisfies coordinates of both points.\r\n" );
document.write( "I leave this check to you, since it is pure mechanical job.\r\n" );
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document.write( "Solved.\r
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