Find the Slope of a Line

Algebra-2

1. Fundamental Concepts

  • Slope Definition: The slope of a non-vertical line is the ratio of the vertical change (rise) to the horizontal change (run) between two points on the line.
  • Formula: For two points  and  on a line, the slope m is calculated as ,where  represents the vertical change (rise) and  represents the horizontal change (run).

2. Key Concepts

  • Slope Significance:
    • A positive slope () means the line rises from left to right.
    • A negative slope () means the line falls from left to right.
    • A zero slope () indicates a horizontal line (no vertical change).
    • An undefined slope occurs for a vertical line (no horizontal change, as the denominator in the slope formula becomes 0).

3. Examples

  • 1: Find the slope of the line passing through  and .
  • Solution: Using , substitute  and :
  • 2: Find the slope of the line passing through  and .
  • Solution: Substitute  and :
  • 3: Find the slope of the line passing through  and .
  • Solution: Substitute  and :

4. Problem-Solving Techniques

  • Step 1: Identify the coordinates of the two points, labeling them as  and  (order does not affect the result).
  • Step 2: Calculate the vertical change by finding the difference in the y-coordinates: .
  • Step 3: Calculate the horizontal change by finding the difference in the x-coordinates: .
  • Step 4: Divide the vertical change by the horizontal change to get the slope, using the formula .
  • Step 5: Determine the nature of the slope (positive, negative, zero, or undefined) based on the result.