Slope of y-axis

[user20]

Is the slope of the y-axis positive?

[RJV]

Slope of y-axis is not defined.

consider the line AO,
where A(0,4) and O(0,0).
The slope will be :

slope = \frac{y2 - y1}{x2 - x1} = \frac{4 - 0}{0 - 0} = \frac{4}{0} = undefined