# Denominator after simplification: denom

### 5.32.4 Denominator after simplification: denom

The denom command finds the denominator of a rational function, after it has been reduced. (See also 5.7.4.)

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

#### Examples.

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

  1

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

  x−1