# Denominator: getDenom

### 5.32.3 Denominator: getDenom

The getDenom command finds the denominator of an unreduced rational function.

- getDenom takes one argument:
  rat, a rational function.
- getDenom(rat) returns the denominator of rat.

Unlike denom (see Section 5.32.4), textttgetDenom does not simplify the expression before extracting the denominator.

#### Examples.

- Input:
  getDenom((x^2-1)/(x-1))
  Output:

  x−1

- Input:
  getDenom((x^2+2*x+1)/(x^2-1))
  Output:

  x2−1