The question is asking for the axes on which the real and imaginary parts of a complex number are plotted on a complex plane.

In the form $a + bi$ (where $a$ is the real part and $b$ is the imaginary part), we can fill in the blanks as follows:

• The real part of the complex number (which is $a$) is plotted on the horizontal (x) axis.
• The imaginary part of the complex number (which is $b$) is plotted on the vertical (y) axis.

Thus, the complete sentence would be:

"For a complex number in the form of $a + bi$, the real part of the complex number is plotted on the x-axis and the imaginary part of the complex number is plotted on the y-axis of a complex plane."

Would you like further details or explanations?

Here are five questions related to this topic:

1. How do you represent a complex number geometrically on a complex plane?
2. What is the significance of the modulus of a complex number in geometry?
3. How can the argument (angle) of a complex number be determined from the real and imaginary parts?
4. What is the relationship between polar and rectangular forms of complex numbers?
5. How do you add and subtract complex numbers geometrically?

Tip: When plotting complex numbers, always remember that the x-axis corresponds to the real part and the y-axis corresponds to the imaginary part.