1. Create a function gaussian_elimination that performs the gaussian elimination of linear system of the form Ax - b. 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 Ux -f when U is an upper triangular matrix. The function header should look something like function x - backward_substitution (U,f) Let us recall that the output has to be a vector. Apply the two functions to solve the 7 x 7 linear system 6 1 7 761 8 7 5 5 278 7 9 5 3 444 3 9 81 6-1 8 2 1 4 5 3337 1 3274 79 6 6 -2 3233 4 ? T3 Call, U, f, x the results. compare your solution to x0 obtained with the Matlab command A\b. Call Err the absolute error. Comment using %