Question 1080154
Slope is change in y over change in x.
So use (0,0) as the starting point.
So then the slope is,
{{{m=(y-0)/(x-0)=y/x}}}
Assume x is 1 for simplicity.
So then your point is (1,y) and
{{{m=y}}}
So for positive,
{{{m>0}}}
{{{y>0}}}
Choose any positive y.
And for negative,
{{{m<0}}}
{{{y<0}}}
Choose any negative y,
And for zero slope,
{{{m=0}}}
{{{y=0}}}
Your point would be (1,0).
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For undefined slope, we go back to the definition of slope.
{{{m=(y-0)/(x-0)}}}
The slope is undefined if the denominator equals zero since division by zero is undefined,
{{{x-0=0}}}
{{{x=0}}}
So then the points are (0,y) where y is any number. 
This is a vertical line at {{{x=0}}}.