How to Find Intervals of Increase and Decrease

Common Mistakes
  • Mixing up x with y
  • Using x-intercepts

Video Length: 6:10

How can you tell if a function is increasing or decreasing?

In this video, I show you a simple way to find intervals of increase and decrease by reading a graph from left to right. Instead of memorizing rules, you’ll learn how to recognize whether a function is moving upward or downward as the x-values increase.

You’ll learn:

• What it means for a function to be increasing
• What it means for a function to be decreasing
• How to read intervals from a graph
• How to write your answers using interval notation
• Common mistakes students make

This lesson is perfect for Algebra 1, Algebra 2, Precalculus, ACT Math, and SAT Math preparation.

📝 Key Question:
As you move from left to right, is the function going up or going down?

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