x 2 + 9 has no (Real) factors (Unlike x 2 − 9 )
Explanation:
The most you could do with this is use the quadratic formula on
XXXX x 2 + 0 ⋅ x + 9
to get
XXXX ± 3 i
So you could factor using Complex values:
XXXX x 2 + 9 = ( x + 3 i ) ( x − 3 i )
