x 2 − 4 x + 24 is of the form a x 2 + b x + c with a = 1 , b = − 4 and c = 24 .
This has discriminant
Δ = b 2 −4a c = ( − 4 ) 2 − ( 4 × 1 × 24 ) = 16 − 96 = − 80
Since Δ < 0 , x 2 − 4 x + 24 = 0
has 2 complex, non-real roots and x 2 − 4 x + 24
has no linear factors with real coefficients.
In other words x 2 − 4 x + 24
is already in simplest terms for real coefficients.