Indeed, as Khayyam writes, the contributions by earlier writers such as al-Mahani and al-Khazin were to translate geometric problems into algebraic equations (something which was essentially impossible before the work of al-Khwarizmi).
Sa katunayan, bilang Khayyam magsusulat, ang mga kontribusyon ng mas maaga writers tulad ng al-Mahani at al-Khazin ay upang isalin geometriko problema sa algebraic equation (isang bagay na kung saan ay mahalagang imposibleng bago ang gawain ng al-Khwarizmi).