Linear Growth and Decay
SAT Math — Algebra & Problem Solving | Master the most frequently tested linear model concepts
1. Linear vs. Exponential — Know the Difference
📈 Linear
- Constant AMOUNT added or subtracted each period
- "Increases by 50 each year"
- "Decreases by 3 per hour"
- Formula: y = mx + b
- Graph: Straight line
📈 Exponential
- Constant PERCENT multiplied each period
- "Increases by 5% each year"
- "Doubles every 3 hours"
- Formula: y = a · bt
- Graph: Curved line
🚨 SAT TRAP: "Increases by 10" → LINEAR (adds 10). "Increases by 10%" → EXPONENTIAL (multiplies by 1.10). Read carefully — one word changes everything!
Visual Comparison: Linear vs. Exponential Growth
Interactive visualization — available in the full lesson
Notice: The linear function is a straight line. The exponential function curves upward, eventually growing much faster.