Consider the linear system 421 +12-13 = 5 -1 +37 + x3 = -4 2x +22 +5x3 = 1 In answering the following questions use 4 decimal place accuracy with rounding: (1.1) Write the system as a matrix equation. (1.2) Use the appropriate Matlab/Octave command to check what the actual solution is. (1.3) Solve the system using: (a) Gaussian elimination without pivoting. (b) Gaussian elimination with scaled partial pivoting. (c) Basic LU decomposition. (1) (2) (7)