2.5. General investigation of the function 2.5.1. Decreasing and increasing function

Function called increasing in the interval if for any two points x ₁ and x ₂ such that inequality holds .

Function called decreasing in the interval if for any two points x ₁ and x ₂ such that inequality holds .

If for any point inequality holds then function increases in the interval .

If for any point inequality holds then function decreases in the interval .

The intervals of increase and decrease of a function are called the intervals of monotonicity of the function.