1. Calculating gradients

2. Rise = how far up Run = how far across
The gradient of a straight line is an indication of how steep a straight line is.
When we draw graphs the method we use to calculate the gradient is:
Rise = how far up
Run = how far across

3. Calculate the gradient of a horizontal line:
The slope of a horizontal line is always zero

4. Calculate the gradient of a vertical line:
The slope of a vertical line is undefined because we cannot divide by zero

5. Summary
Negative slope
Positive slope
Zero slope
Undefined slope

6. Example: Calculate the gradient joining (-1,-3) to (5, 2)
run = 6
rise = 5
How could we calculate gradient without drawing the diagram?

7. How can we calculate the gradient joining (x1,y1) to (x2,y2)?
run = x2-x1
(x2,y2)
rise = y2-y1
(x1,y1)

8. So, to summarise: Use when drawing graphs
Use when graphs are not needed

9. Calculate the gradients of the line joining (4,-7) to
(-2,-1):
(4, -7) (-2, -1)
(x1,y1) (x2,y2)

10. (5, -3) (k, -1)
(x1,y1) (x2,y2)