Let P ∈ R [ X ] {\displaystyle {}P\in \mathbb {R} [X]} be a non-constant polynomial with real coefficients. Prove that P {\displaystyle {}P} can be written as a product of real polynomials of degrees 1 {\displaystyle {}1} or 2 {\displaystyle {}2} .
![{\displaystyle {}P\in \mathbb {R} [X]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/9bf6bcf64e16c3ac6b30ecd6577e72648ab2325a)
