← 2.2 Equations of Straight Lines
Positive, negative, zero and undefined
Mathematics · Grade 9 · about 40 minutes
The sign of the gradient says whether a line rises or falls; flat lines give zero and vertical lines have none.
Sign in to read this lesson
Lessons are for learners and teachers with an account. Browsing the curriculum — subjects, strands and what each sub-strand covers — stays open to everyone.
- 9 sections of explanation, worked examples and diagrams
- 1 practice task with hints and worked answers
- A quiz that marks itself as you go
- Your progress kept across every subject you take
Other lessons in this sub-strand
- Steepness we can see
- Gradient as rise over run
- Gradient from two known points
- Positive, negative, zero and undefined
- Gradients on a building site
- A line from one point and a gradient
- A line through two points
- The form y = mx + c
- What m and c do to the line
- Rearranging into y = mx + c
- The y-intercept
- The x-intercept
- Sketching a line from its intercepts
- Straight-line stories: charges and rates
- Gradients and lines at work in Kenya