# Mathematics: Relations and Functions-I: Logarithmic, Identify and Constant Functions

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## Logarithmic Functions

• Now consider the function

• We write it equivalently as , thus is the inverse function of

• The base of the logarithm is not written if it is and so is usually written as.

## Identity Function

Let be the set of real numbers. Define the real valued function by for each. Such a function is called the identity function. Here the domain and range of are. The graph is a straight line. It passes through the origin.

## Constant Function

Define the function by where is a constant and each. Here domain of is and its range is . The graph is a line parallel to axis.

Example:

for each

## Signum Function

The function defined by following function is called a Signum function.