Nothing happens yet, I attach the screenshots. As you can see the values of x and a are null. There is also something strange about solving the equation with the variables "u" and "v" since the command solve the manual says that it is useful for any variable and you can see that with these variables the answer is an empty vector, I do not understand why either. But with the "x" and "y" variables, the error message appears. I'll try restoring with ON + Symb key. Could you tell me if you are given the correct answer to which CAS or HOME settings?