His student Lodovico Ferrari solved the quartic polynomial, which solution Cardano also included in Ars Magna.
From the en.wikipedia.org
Usually, a polynomial of degree n, for n greater than 3, is called a polynomial of degree n, although the phrases quartic polynomial and quintic polynomial are sometimes used.
From the en.wikipedia.org
Since a quartic function is a polynomial of even degree, it has the same limit when the argument goes to positive or negative infinity.