What is the slope of the line that contains (1,6) and (1,-9)

The formula for slope is (y2 - y1) / (x2 - x1).
Substitute your values, and you get (-9 - 6) / (1 - 1), or -15 / 0
Because anything divided by zero is undefined, The line is vertical, so it has no slope. The answer is undefined

M= (y2-y1)/ (x2-x1)

Plug the points in.

-9-6/1-1

-15/0 or -15. The slope of the line is -15.

I hope this helped you!

Brainliest answer would be greatly appreciated!