Question

5. Which of the following is always true about

the graph of a horizontal line?
A. The graph will have a positive y-intercept.
B. The graph will have a negative y-intercept.
C. The slope of the graph will be undefined.
D. The slope of the graph will be zero.

Answer 1

D. The slope of the graph will be zero.

Explanation:

Slope of a line is given as
`(rise)/(run) = (y_2 - y_1)/(x_2 - x_1)`.

For a horizontal line, the rise is always equal to zero since the line doesn't rise vertically. This means,
`y_2 - y_1 = 0`.

No matter the value of the run,
`x_2 - x_1`, when we divide zero by the value of the run, we would always have 0.

Therefore, the slope of an horizontal line would always be zero.