Quasielliptic operators and equations not solvable with respect to the highest order derivative

We consider a class of quasielliptic operators in the whole space. Isomorphism properties in special weighted Sobolev spaces are established. We obtain conditions for unique solvability of the quasielliptic equations and estimates for their solutions in more general weighted spaces. Using the established results, we study solvability of the initial value problem for equations not solvable with respect to the highest order derivative.