Exact values of rational roots of a polynomial : rationalroot

### 2.29.3 Exact values of rational roots of a polynomial :
`rationalroot`

`rationalroot` takes 1 or 3 arguments : a polynomial and optionnally two reals numbers α,β.

- If `rationalroot` has 1 argument, `rationalroot` returns the list of the value of the rational roots of the polynomial without multiplicity.
- If `rationalroot` has 3 arguments, `rationalroot` returns only the rational roots of the polynomial which are in the interval [α,β].

To find the rational roots of 2*x3−3*x2−8*x+12, input:

`rationalroot(2*x```^```3-3*x```^```2-8*x+12)`

Output :

`[2,3/2,-2]`

To find the rational roots of 2*x3−3*x2−8*x+12 in [1;2], input:

`rationalroot(2*x```^```3-3*x```^```2-8*x+12,1,2)`

Output :

`[2,3/2]`

To find the rational roots of 2*x3−3*x2+8*x−12, input:

`rationalroot(2*x```^```3-3*x```^```2+8*x-12)`

Output :

`[3/2]`

To find the rational roots of 2*x3−3*x2+8*x−12, input:

`rationalroot(2*x```^```3-3*x```^```2+8*x-12)`

Output :

`[3/2]`

To find the rational roots of (3*x−2)2*(2x+1)=18*x3−15*x2−4*x+4, input:

`rationalroot(18*x```^```3-15*x```^```2-4*x+4)`

Output :

`[(-1)/2,2/3]`