hello dear friend my lecture is about Khayyam

:: Mathematician

Omar Khayyam was famous during his times as a mathematician. He wrote the influential Treatise on Demonstration of Problems of Algebra (1070), which laid down the principles of algebra, part of the body of Arabic Mathematics that was eventually transmitted to Europe. In particular, he derived general methods for solving cubic equations and even some higher orders: 

From the Indians one has methods for obtaining square and cube roots, methods which are based on knowledge of individual cases, namely the knowledge of the squares of the nine digits 12, 22, 32 (etc.) and their respective products, i.e. 2 × 3 etc. We have written a treatise on the proof of the validity of those methods and that they satisfy the conditions. In addition we have increased their types, namely in the form of the determination of the fourth, fifth, sixth roots up to any desired degree. No one preceded us in this and those proofs are purely arithmetic, founded on the arithmetic of The Elements. - Omar Khayyam: Treatise on Demonstration of Problems of Algebra   

His method for solving cubic equations worked by intersecting a conic section with a circle (examples[5]). Although this approach had been used earlier by Menaechmus and others, Khayyám provided a generalization extending it to all cubics with positive roots. In addition he discovered the binomial expansion. His method for solving quadratic equations is also similar to what is used today.

In the Treatise he also wrote on the triangular array of binomial coefficients known as Pascal's triangle. In 1077, Omar wrote Sharh ma ashkala min musadarat kitab Uqlidis (Explanations of the Difficulties in the Postulates of Euclid). An important part of the book is concerned with Euclid's famous parallel postulate, which had also attracted the interest of Thabit ibn Qurra. Al-Haytham had previously attempted a demonstration of the postulate; Omar's attempt was a distinct advance, and his criticisms made their way to Europe, and may have contributed to the eventual development of non-Euclidean geometry. 

Omar Khayyám also had other notable work in geometry, specifically on the theory of proportions.