Bījagaṇita

Bījagaṇita ('computation with seeds', that is, with unknowns) is the Indian name for algebra, as distinct from vyakta-gaṇita, the arithmetic of known quantities. Brahmagupta (7th century) treated linear indeterminate equations (kuṭṭaka) and the square-nature equation (vargaprakṛti), and Bhāskara II's Bījagaṇita (1150) gives a systematic treatment including negative quantities and the cakravāla method. Unknowns were named by colour words such as yāvat-tāvat, kālaka and nīlaka.