## Critical numbers

### In mathematics, critical numbers are the values where a function can undergo a change in behavior

In mathematics, critical numbers are the values where a function can undergo a change in behavior. More specifically, critical numbers occur when the derivative of a function is equal to zero or does not exist.

To understand critical numbers, we need to consider the concept of differentiation. The derivative of a function represents its rate of change at any given point on its graph. If the derivative is positive, the function is increasing, and if the derivative is negative, the function is decreasing.

A critical number occurs when the derivative is equal to zero or undefined. At these points, the rate of change of the function may shift, leading to important information about the function’s behavior.

There are three different types of critical numbers:

1. Relative maximum or minimum: These occur when the derivative changes sign from positive to negative (a peak or maximum point) or from negative to positive (a valley or minimum point). These critical numbers help identify the highest or lowest point(s) of a function.

2. Vertical tangent or cusp: These occur when the derivative is undefined at a particular point. These critical numbers indicate a sharp turn or corner on the graph.

3. Point of inflection: These occur when the derivative changes from increasing to decreasing or vice versa, without changing sign. These critical numbers indicate a change in the concavity of the graph.

To find critical numbers, follow these steps:

1. Determine the derivative of the function.

2. Set the derivative equal to zero, and solve for the variable(s). These solutions will be the critical numbers.

3. Check if the derivative exists at any other points where it is not equal to zero.

By identifying the critical numbers of a function, we can gain insights into its extrema (maximum and minimum values), points of inflection, and important shifts in behavior.

##### More Answers:

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How to Determine if a Function is Decreasing | Analyzing Derivatives and Graphs