Question

A line parallel to the ___ has no defined slope, and a line parallel to the ___ has a slope of zero.

the options for the first blank are
x-axis
y-axis

the options for the second blank are
x-axis
y-axis

Answer 1

the answer for the fist line is y-axis and the second line is x-axis 

Answer 2

Answer: A line parallel to the y axis has no defined slope, and a line parallel to the x axis has a slope of zero.

Explanation:

The slope of a line is given by :-

`\text{Slope}=\frac{\text{Change in y}}{\text{Change in x}}`

Let
`y=a` be a line that is parallel to x axis.

Here, change in y = 0

Then slope of line
`y=a` wil be :-

`\text{Slope}=\frac{0}{\text{Change in x}}=0`

Let
`x=a` be a line that is parallel to y axis.

Here, change in x = 0

Then slope of line
`x=a` wil be :-

`\text{Slope}=\frac{\text{Change in y}}{0}`= not defined

Hence, A line parallel to the y axis has no defined slope, and a line parallel to the x axis has a slope of zero.