# Rate of Change

A rate of change is a rate that describes how one quantity changes in relation to another quantity. If x is the independent variable and y is the dependent variable, then

Rates of change can be positive or negative. This corresponds to an increase or decrease in the y -value between the two data points. When a quantity does not change over time, it is called zero rate of change.

### Positive rate of change

When the value of x increases, the value of y increases and the graph slants upward.

### Negative rate of change

When the value of x increases, the value of y decreases and the graph slants downward.

### Zero rate of change

When the value of x increases, the value of y remains constant. That is, there is no change in y value and the graph is a horizontal line.

Example:

Use the table to find the rate of change. Then graph it.

A rate of change is a rate that describes how one quantity changes in relation to another quantity.

The rate of change is or 40. This means a vehicle is traveling at a rate of 40 miles per hour.