1. Create a function gaussian_elimination that performs the gaussian elimination of linear system of the form Ab. The function should return the associated upper triangular matrix Uand the modified right-hand side f. The function header should look something like function [U,f -gaussian_elimination (A, b) Create a function backward-substitution that solve the system Uz = f when U is an upper triangular matrix. The function header should look something like function backward substitution (U, F) Let us recall that the output has to be a vector Apply the two functions to solve the 7 7 linear system 61 7 761 8 7 5 5 2 7 8 7 6 9 8 1 6-1 8 2 14 5 3 3 37 6 6 -2 3 2 3 3 T7 9 Call, U,f,x the results. compare your solution to x0 obtained with the Matlab command Ab. Call Err the absolute error. Comment using %