The rootof command finds the value of one polynomial at a root of another.
In exact computations, Xcas will rewrite rational evaluations of rootof as a unique rootof with degree(P)<degree(Q). If the resulting rootof is the solution of a second degree equation, it will be simplified.
Example.
Let α be the root with largest imaginary part of
Q(x)=x4+10x2+1 (all roots of Q have real part
equal to 0).
−i | ⎛ ⎜ ⎝ | − | √ |
| + | √ |
| ⎞ ⎟ ⎠ |
−2 | √ |
| −5 |