In mathematics, a quadratic algebra is a filtered algebra generated by degree one elements, with defining relations of degree 2. It was pointed out by Yuri Manin that such algebras play an important role in the theory of quantum groups. The most important class of graded quadratic algebras is Koszul algebras.
People who know quadratic algebra know about Koszul 
Just because you can learn how to solve a quadratic equation doesn't mean you'll learn who Koszul was or why he was important to math. But if you specialize in algebra, you will probably know who this is.
( z1 know :ARG0 ( z2 person :ARG0-of ( z3 know :ARG1 ( z4 algebra :mod ( z5 quadratic ) ) ) ) :ARG1 ( z6 person :name ( z7 name :op "Koszul" ) ) )