You can
put this solution on YOUR website!The statement is TRUE. The definition of the slope of a line is:

This is the same as:
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If a line is running parallel to the x axis, the x value is changing but the change in y values is zero. So for a line parallel to the x axis,

So the slope equates to zero.
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If a line is running parallel to the y axis, the y value is changing, but the change is x values is zero. So for a line parallel to the y axis,

Having a zero denominator means this expression is undefined, so this line has no slope.
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Good Luck,
tutor_paul@yahoo.com