Sridhara

Sridhara (870–930) was an Indian mathematician known for two treatises: Trisatika (sometimes called the Patiganitasara) and the Patiganita. At least three other works have been attributed to him, namely the Bijaganita, Navasati, and Brhatpati. Sridhara gives rules for operating with rational fractions. He gives a wide variety of applications including problems involving ratios, barter, simple interest, mixtures, purchase and sale, rates of travel, wages, and filling of cisterns.

Sridhara was one of the first mathematicians to give a rule to solve a quadratic equation.
"Multiply both sides of the equation by a known quantity equal to four times the coefficient of the square of the unknown; add to both sides a known quantity equal to the square of the coefficient of the unknown; then take the square root. "

Courtesy : Internet