m is the slope (how fast y changes). b is the y-intercept (where the line crosses the y-axis). If b ≠ 0, the relationship is nonproportional — it does NOT go through the origin!
1
Sara's phone: $20 down + $5 per month
y = 5x + 20 (m = 5, b = 20)
2
y = kx vs y = mx + b: Proportional lines pass through (0, 0). Adding b shifts the line up or down.
3
Spot b on a graph: Find where the line crosses the y-axis. Spot m by counting rise over run.
Filling In a Table
Plug each x-value into the equation to get y.
✓
y = 5x + 20, when x = 3 → y = 5(3) + 20 = 35
✓
y = 5x + 20, when x = 6 → y = 5(6) + 20 = 50
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Notice each month adds +5 — that's the slope in action!
How to Play
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Equation → Graph — Pick the graph that matches the equation. Check b first, then m!
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Equation → Table — Type the missing y-value in the table.
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Mixed — Both types together for the ultimate challenge!
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A calculator is available in the bottom-left corner — but try it in your head first!
