Line cd contains points a (4, -7) and b (4, 8). the slope of line cd is

zero
undefined
positive
negative

To find the slope, you divide the difference of the y-coordinates of a point on a line by the difference of the x-coordinates. It is expressed as:

slope = (y2 - y1) / (x2-x1)
slope = 8-(-7) / 4 - 4
slope = 15 / 0
slope = undefined < SECOND OPTION

The line should be vertical where the slope is undefined. Hope this answers the question. Have a nice day.

Hello there.

Line CD contains points A (4, -7) and B (4, 8). The slope of line CD is 

undefined

Cis your correct answer