It's strange that you are ignoring numbers -1 and 3/2. What about all the complex numbers having imaginary part 3/4: is it also the y axis? So, does the exact value of the imaginary part not matter?Is a) just all the numbers lying on the x axis and b) all numbers lying on the y axis?

The real part of a complex number is its x-coordinate, and the imaginary part is its y-coordinate.