Answer:
On the horizontal axis
Step-by-step explanation:
The complex number is represented by the complex plane or z-plane which is the representation geometrically of the real (number) axis and the imaginary (number) axis
When plotting complex numbers, the real part of the complex number is always plotted on the horizontal axis while the imaginary part is plotted on the vertical axis
The complex plane concept facilitates the description of complex numbers geometrically.