The category of finite dimensional linearizations (or representations)
of homogeneous polynomials is not well known, except for quadratics a
nd binary cubics. As it is equivalent to the study of subvectorspaces
of matrix algebras all elements of which have their d power equal to a
scalar, we study 3-dimensional representations of ternary and quatern
ary cubics and we obtain another proof of a result of Van den Bergh.