1. Fundamental Concepts
- Definition: The rate of change is a measure of how much one quantity changes in relation to another quantity.
- Zero Slope: A zero slope indicates that there is no change in the y-value as the x-value changes, resulting in a horizontal line.
- Equation: The equation of a line with zero slope is given by $$y = b$$ where $$b$$ is a constant.
2. Key Concepts
Basic Rule: $$\text{If } \Delta y = 0 \text{ for any } \Delta x, \text{ then the slope } m = 0.$$
Degree Preservation: The slope of a horizontal line remains constant and equal to zero regardless of the points chosen on the line.
Application: Used to identify constant functions and understand scenarios where there is no change over time or distance.
3. Examples
Example 1 (Basic)
Problem: Determine the slope of the line represented by the equation $$y = 4$$.
Step-by-Step Solution:
- The equation is already in the form $$y = b$$ where $$b = 4$$. This indicates a horizontal line.
- The slope of a horizontal line is always $$0$$.
Validation: Since the line is horizontal, any two points on the line will have the same y-coordinate, confirming the slope is $$0$$.
Example 2 (Intermediate)
Problem: Given two points $$(3, 5)$$ and $$(7, 5)$$, find the slope of the line passing through these points.
Step-by-Step Solution:
- Use the slope formula: $$m = \frac{\Delta y}{\Delta x} = \frac{y_2 - y_1}{x_2 - x_1}$$.
- Substitute the points: $$m = \frac{5 - 5}{7 - 3} = \frac{0}{4} = 0$$.
Validation: Since both points have the same y-coordinate, the line is horizontal, and the slope is confirmed to be $$0$$.
4. Problem-Solving Techniques
- Visual Strategy: Graph the line to visually confirm if it is horizontal.
- Error-Proofing: Always check if the y-coordinates of any two points on the line are the same.
- Concept Reinforcement: Understand that a zero slope means the function value does not change with respect to the independent variable.