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mth 158
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** Question Form_labelMessages **
slope undefined
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How do you know which answer to find with point (2,4)
if the answer is x = 2 ; why wouldn't it be y = 4
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The slope of any line is defined, except for a vertical line.
On a vertical line the run between any two points on the line is zero. So when calculating rise / run, we have 0 in the denominator, making the result undefined.
If the line is horizontal then the rise between any two distinct points is 0, and the slope is therefore 0 (the 0 occurs in the numerator, and the run is not zero, so the slope is in this case 0).
Both the lines x = 2 and y = 4 pass through the point (2, 4). But the line y = 4 is horizontal, having slope 0, which is perfectly well-defined.
The line x = 2, however, is vertical, with undefined slope.
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