How do I find if a slope is defined?

Question

daniel14 · Answer

examples?

anonymous · Answer

The slope is defined as long as the line isn't vertical. If two points have the same x-coordinate, the slope isn't defined.

unklerhaukus · Answer

The slope of a straight line is defined as the ratio of of the change in y-coordinate, to the change in x-coordinate:
$$m = \frac{\Delta y}{\Delta x} = \frac{y_2-y_1}{x_2-x_1}$$

As @peachpi points out, if $x_2$ is the same value  as $x_1$, the fraction get a zero in the denominator. A fraction with a zero in the denominator is not mathematically equal to any number, meaning the slope would be undefined in this case.

anonymous · Answer

|dw:1455345424086:dw| This is an example of an undefined slope.