English: So, alpha is a root of f also right, this is clear because, f of alpha is g of alpha times h of alpha right, g is a factor of f, so; that means, f is g h. So, f alpha is g alpha times h alpha which is 0 because, g alpha is 0.
Telugu: ఇది స్పష్టంగా ఉంది ఎందుకంటే, f( ఆల్ఫా) = g(ఆల్ఫా)* h( ఆల్ఫా), g అనేది f యొక్క ఫ్యాక్టర్ , అంటే, f అనేది g h.