1. write what you know about this phrase. preview: nonlinear function

Brief Explanations:

A nonlinear function is a function whose graph is not a straight - line. It does not follow a linear relationship between the input (independent variable) and output (dependent variable). For example, quadratic functions like $y = ax^{2}+bx + c$ ($a\neq0$), exponential functions like $y = a^{x}$ ($a>0,a\neq1$), and trigonometric functions such as $y=\sin(x)$ are nonlinear functions. Nonlinear functions are widely used in various fields like physics, engineering, and economics to model complex real - world phenomena.

Answer:

A nonlinear function is a function whose graph is not a straight line and does not follow a linear relationship between variables. It includes quadratic, exponential, and trigonometric functions among others and is used to model complex real - world situations.