What is how to find critical points?

Here's how to find critical points of a function:

Definition: A critical point of a function f(x) is a point in the domain of f where either:

  1. The derivative of f(x) is equal to zero, i.e., f'(x) = 0. This means the tangent line to the graph of f(x) is horizontal at that point. These points are often where local maxima or local minima occur. See: Extrema and Local%20Extrema.

  2. The derivative of f(x) is undefined. This can happen at sharp corners, vertical tangents, or points where the function is not differentiable.

Steps to Find Critical Points:

  1. Find the derivative: Calculate the first derivative of the function, f'(x).

  2. Set the derivative to zero: Solve the equation f'(x) = 0 for x. The solutions are the x-values where the tangent line is horizontal.

  3. Find where the derivative is undefined: Determine the x-values for which f'(x) is undefined. This often involves looking for denominators that could be zero, or points where the function involves radicals or piecewise definitions that result in a non-differentiable point.

  4. Check the domain: Make sure that the x-values found in steps 2 and 3 are actually in the domain of the original function f(x). Points that are not in the domain are not critical points.

  5. Critical Points: The x-values that satisfy the conditions in steps 2, 3, and 4 are the x-coordinates of the critical points. To find the y-coordinates of the critical points, plug the x-values back into the original function f(x) to get the corresponding y-values. The critical points are then expressed as ordered pairs (x, f(x)).

Importance:

Critical points are important for: