Question

A vertical line:

O has an undefined slope.
O has a slope of zero.
O has a midpoint equal to half its length.
O doesn't have an equation.
O has no real solutions.

Answer 1

Has an undefined slope

Explanation:

The slope formula is y2-y1 / x2-x1.

When the x values are the same, like they are in a vertical line, you get 0 in the denominator. You can't divide by 0, so the slope is undefined