The $LU$ decomposition method applied to the linear system $[A]\{x\}=\{b\}$ is $($assume that the matrix $A$ is fully populated$)$

requires finding the lower and upper factors of the matrix $[$A$]$ by one of three possible choices

is used when the coefficient matrix $[$A$]$ stays constant and there are multiple right hand sides $\{b\}$ to solve

is a direct method of solution

is a method that takes $O(N^3)$ floating point operations to solve the system of equations for the first right hand side vector $[$b$]$ and

subsequently takes $O(N^2)$ for any new right hand side vector $\{b\}$

is an iterative method of solution