Master graphing linear relations on the coordinate plane. Grade 9 Alberta mathematics lesson.
Lesson 4.2 of Linear Relations in Grade 9 Math: Alberta curriculum lessons.
🟩 The Cartesian Coordinate System. The Cartesian plane helps us show how two quantities are related.
📏 The x-axis (Horizontal Line). The horizontal line is called the x-axis
📏 The y-axis (Vertical Line). The vertical line is called the y-axis
These two axes divide the plane into four quadrants:
💡 Remember. Each point on the plane is written as an ordered pair: (x, y).
🟦 What is (x, y)?. A point consists of two coordinates: (x, y)
1️⃣ The First Number (x). The first number represents x, how far to move horizontally.
2️⃣ The Second Number (y). The second number represents y, how far to move vertically.
✅ Important Rule. X always goes first!
🧭 Steps to Plot a Point.
📐 Linear Relations. A linear relation shows a steady, consistent pattern between two quantities.
💼 Example: Hourly Earnings. You earn 15 for every hour you work.
✅ Why is this Linear?. Each hour, your money goes up by the same amount (+15). That's what makes it linear.
📈 Linear Graphs. When we graph a linear relation, the points form a straight line.
✅ Linear Graphs.
❌ Non-Linear Graphs.
🔵 Discrete vs Continuous Graphs. Some graphs show separate points, while others show a smooth line.
🔵 Discrete Data. Discrete data = values that are counted
🟢 Continuous Data. Continuous data = values that are measured
📝 A: Plot (3, 2).
📝 B: Plot (−2, −4).
📝 C: Plot (−3, 5).
📝 D: Plot (4, −3).
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