= Consider a preconditioner matrix M to solve a left-preconditioned linear system M-1Ax M-16 by using an iterative linear solver (e.g. conjugate gradient method). Which of the following claims are true? There may be more than one correct answer. -2 marks for each incorrect answer. If the matrix A is symmetric, then the preconditioned matrix M-1 A is also symmetric. Using a preconditioner will make the linear solver iterations faster to compute. The inverse preconditioner matrix M-1 needs to be explicitly computed and stored. The preconditioner can be obtained by solving a simplified version of the full problem. The preconditioner M should be chosen to reduce the condition number k(M-1A)