Constant function

In mathematics, a constant function is a function whose (output) value is the same for every input value. For example, the function ${\displaystyle y(x)=4}$ is a constant function because the value of  ${\displaystyle y(x)}$  is 4 regardless of the input value ${\displaystyle x}$ (see image).

As a real-valued function of a real-valued argument, a constant function has the general form  ${\displaystyle y(x)=c}$  or just  ${\displaystyle y=c}$  .

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