Complex sentence: To show this they use the following corollary to the theorem by Obreschkoff of 1920-1923 mentioned earlier; that is, the following corollary gives the necessary conditions under which a polynomial with one positive root has exactly one sign variation in the sequence of its coefficients.
Split into simpler sentences: To show this they use the following corollary to the theorem by Obreschkoff of 1920-1923 mentioned earlier. The following corollary gives the necessary conditions under which a polynomial with one positive root has exactly one sign variation in the sequence of its coefficients.