Question

the slope of a horizontal line is ______.
0
positive
undefined
1

Explanation:

The slope of a line is calculated as \( \frac{\text{change in } y}{\text{change in } x} \) (i.e., \( m=\frac{y_2 - y_1}{x_2 - x_1} \)). For a horizontal line, the \( y \)-coordinates of all points are the same, so \( y_2 - y_1 = 0 \). Thus, the slope \( m=\frac{0}{x_2 - x_1}=0 \) (as long as \( x_2
eq x_1 \), and for a horizontal line, \( x \) can change but \( y \) doesn't, so the denominator is non - zero in the slope formula application here). A positive slope is for lines rising from left to right, undefined slope is for vertical lines (where \( x_2 - x_1 = 0 \)), and a slope of 1 is for lines with equal rise and run. So the slope of a horizontal line is 0.

Answer:

A. 0