 Hello and welcome to the session. It is because the following problem today shows that the signal function f's are that r goes to r given by fx is equal to 1, if x is greater than 0, 0 if x is equal to 0 and minus 1 if x is less than 0 is neither 1, 1 nor on 2. Now let us write the solution. Now let us check for 1, 1. First for x greater than 0 let x1, x2 belongs to r set of positive real number then f of x1 is equal to f of x2 is equal to 1 in all cases but x1 is not equal to x2 thus f is not 1, 1. Now the second case x is less than 0 let x1, x2 belongs to set of negative real numbers then f of x1 is equal to f of x2 which is equal to minus 1 in all cases even if x1 not equal to x2 thus f is not 1, 1. Now the third case x is equal to 0 f is 1, 1 for x is equal to 0 but function is not 1, 1 since we have proved it is not 1, 1 for x greater than 0 and x less than 0 hence f is not 1, 1 for all x. Now let us check for on 2. Here co-domain is a set of real numbers but range is minus 1, 0, 1 so clearly range is not equal to co-domain f is not on 2. I hope you understood the problem bye and have a nice day.