Matlab coding problem. What needs to be changed here to pass all the pretests?

Here is my coding and the error message.

This is the problem.

Your Function 1 function [xroot, residual, ea, iter-count] student-solution(fun, x, es, max-it, varargin) = 4 x(2)-xi(2); 6 if nargin 0,error('no sign change),end 9 if nargin