Question

which best describes the slope of a horizontal line?
a) 0
b) positive
c) negative
d) undefined

Explanation:

Step1: Recall Slope Formula

The slope \( m \) of a line is given by \( m = \frac{y_2 - y_1}{x_2 - x_1} \), where \( (x_1, y_1) \) and \( (x_2, y_2) \) are two points on the line.

Step2: Analyze Horizontal Line

For a horizontal line, the \( y \)-coordinates of all points are the same. So, \( y_2 - y_1 = 0 \). Substituting into the slope formula, \( m = \frac{0}{x_2 - x_1} = 0 \) (as long as \( x_2
eq x_1 \), but for a horizontal line, \( x \) can vary, and \( y \) is constant). A positive slope is for lines rising from left to right, negative for falling, and undefined is for vertical lines (where \( x_2 - x_1 = 0 \)).

Answer:

A) 0