Answer:
1st one: slope = undefined
2nd one: slope = undefined
Explanation:
The slope of a line is a measure of its steepness. It is calculated by dividing the change in the y-coordinate by the change in the x-coordinate between two points on the line.
Formula:

1st one:
Slope of the line passing through the points (4, 2) and (4, -8) is:
![\sf Slope = ( -8-2)/(4-4) \\\\ = - (10)/(0) \\\\ = \sf Undefined]()
2nd one:
Slope of the line passing through the points (-8, -9) and (-8, 9) is:
![\sf Slope = ( 9-(-9))/(-8-(-8)) \\\\ = - (9+9)/(-9+8) \\\\ = (18)/(0) \\\\ = \sf Undefined]()
As we can see, both slopes are undefined. This is because the two points in each case have the same x-coordinate. A line with an undefined slope is a vertical line.