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Complex Numbers

Work with imaginary and complex numbers and the complex plane.

18 Lessons237 Exercises

The Square Root of -1

Imaginary Numbers

Complex Numbers

Plotting Complex Numbers

Identifying Complex Points

Combining Complex Numbers

Adding Complex Numbers

Subtracting Complex Numbers

Absolute Value

Complex Separation

Scalar Multiplication

Scaling Magnitudes

Simplifying Expressions

Multiplying by i

Rotation by Multiplication

Multiple Rotations

Scaling and Rotating

General Multiplication


Course description

In this course you'll understand how complex numbers arise naturally as solutions to equations. You'll learn to manipulate them according to the usual rules of algebra and derive geometric insights from the complex plane.


Topics covered

  • Complex numbers as solutions to quadratic equations.
  • Addition and subtraction of complex numbers.
  • Absolute value and scaling of complex numbers.
  • Multiplying complex numbers algebraically.
  • The geometric interpretation of complex multiplication.
  • Complex conjugates.
  • Dividing complex numbers.
  • Complex numbers in polar form.
  • Powers and roots.

Prerequisites and next steps

Assumes comfort with the cartesian and polar coordinate plane, quadratic equations and basic trigonometry.