#### What are complex numbers?

A complex number can be written in the form a + b*i* where a and b are real numbers (including 0) and *i* is the imaginary number *i*

Therefore a complex number contains two 'parts':

- one that is real
- and another part that is imaginary

**Examples** of a complex number

- $$ 3 + 5 i $$
- $$ 12 + \sqrt{-3} $$ ($$\sqrt{-3} $$ is the imaginary part)
- $$ 4 +22i$$
- $$ 11 - i $$
- $$ 12 - \sqrt{-125} $$ ($$\sqrt{-125} $$ is the imaginary part)

#### How do you graph complex numbers?

Complex numbers are often represented on a complex number plane (which looks very similar to a cartesian plane).

- On this plane, the imaginary part of the
**complex part**is measured on the**'y-axis'**, the vertical axis - the
**real part**goes on the**'x-axis'**, the horizontal

**Practice**Problems of complex number

This complex number is in the fourth quadrant.

This complex number is in the 2nd quadrant.

This complex number is in the 3rd quadrant.