Which line has an undefined slope?

Select one:
a. x=18
b. 2y-6x=0
c. y=-9
d. y=x

can you draw them?

a vertical line has a constant which? ... x or y?

The line with an undefined slope is represented by the equation "x = 18." To understand why this line has an undefined slope, we need to examine what the slope represents.

In general, the slope of a line represents how steep it is. It is defined as the ratio of the vertical change (rise) to the horizontal change (run) between any two points on the line.

For example, in the equation "y = mx + b," where m is the slope, we can rewrite it as "y - b = mx". From this form, we can see that the coefficient of x (m) represents the slope of the line.

However, in the equation "x = 18," we only have the value of x and no expression for y. This means that no matter what the value of y is, x will always be equal to 18. In other words, the line consists of all the points where x is equal to 18.

Because there is no variable coefficient for y, there is no ratio of the vertical change to the horizontal change. Therefore, the line x = 18 has an undefined slope.

So, the correct answer to the question is:

a. x = 18.