Question

How do you find the slope for (4,2) and (4,5)?

Answer 1

The line through `(4,2)` and `(4,5)` is vertical and as such has an undefined slope

Explanation:

For two points `(x_1,y_1)` and `(x_2,y_2)` the slope is given by

`m=(Delta y)/(Delta x) = (y_2-y_1)/(x_2-x_1)`

if `(x_2-x_1) != 0`

but in this case `(x_2-x_1) = (4-4) = 0`
and therefore the slope is undefined.