concept check:parallel to y-axis

[syflysun]

if line k is parallel to y-axis, then the slope of line k is

A. not defined
B. not existed
C. infinite
D. others?

I know parallel to x, the slope is 0.

thanks

[KrazyKarl]

I've always learned slope as: Change in Y / Change in X (rise over run). If x doesn't change, then the denominator is 0, so it would be undefined.

[arora007]

y=mx + c

which would mean... if something is parallel to y axis... then x=constant (since x=0 is the Y axis)

y could be anything from 0 to infinity... thus undefined!

[Maciek]

hi syflysun!

This is example of infinite slope.

Consider the linear function:

y = a + bx

b is the slope of the line. Slope means that a unit change in x, the independent variable will result in a change in y by the amount of b.

slope = change in y/change in x = rise/run

Follow this link to see more details:

https://www.columbia.edu/itc/sipa/math/slope_linear.html

Best,
Maciek

[Tani]

The terminology I have always used is an undefined slope. Given slope = change in y over change in x -- if the line is parallel to the y-axis, the change in x is zero. Anything divided by zero is undefined.