Algebra.Com's Answer #335920 by Edwin McCravy(20086)![\"\"](\"/images/stars/stars-13.gif\")  
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Write a standard form of the line that passes through the point (-10,-9), and
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document.write( " (-10,-7)
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document.write( "Notice that when we try to use the slope formula, it fails\r\n" );
document.write( "because division by 0 is not defined:\r\n" );
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document.write( "So not only can't use the slope formula, but\r\n" );
document.write( "we also can't use the slope-intercept formula,\r\n" );
document.write( "or the point-slope formula because those\r\n" );
document.write( "involve the slope, and this line doesn't have \r\n" );
document.write( "any slope!\r\n" );
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document.write( "So let's plot the two given points:\r\n" );
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document.write( "Now we draw a line (in green) through them:\r\n" );
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document.write( "We notice that we have a vertical line, the only kind of line\r\n" );
document.write( "that does not have a slope at all. Horizontal lines have a slope\r\n" );
document.write( "of 0 but vertical lines have no slope at all. Notice the\r\n" );
document.write( "difference between \"having slope 0\" and \"having no slope at all\".\r\n" );
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document.write( "This one has no slope at all.\r\n" );
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document.write( "Let's look at the coordinates of some other points in that line:\r\n" );
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document.write( "Notice that they all have -10 as their x coordinate.\r\n" );
document.write( "So we could write:\r\n" );
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document.write( "\"x-coordinate = -10\"\r\n" );
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document.write( "but instead we take out the \"-coordinate\" and just write\r\n" );
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document.write( " x = -10\r\n" );
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document.write( "And that is a standard form of the line. You may have been told that\r\n" );
document.write( "a standard form of a line is \r\n" );
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document.write( "Ax + By = C\r\n" );
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document.write( "x = -10 is really in that form because it is the same as\r\n" );
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document.write( "1x + 0y = -10, where A=1, B=0, and C=-10,\r\n" );
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document.write( "but it is preferable to leave out the 1 coefficient of x\r\n" );
document.write( "and the term 0y.\r\n" );
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document.write( "So the answer is simply\r\n" );
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document.write( "x = -10\r\n" );
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document.write( "Edwin \n" );
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