Khan Academy Static

Adding_subtracting_complex_numbers

Learn how to add or subtract complex numbers. For example, write (2+3i)-(1+2i) as (1+i).

Challenging_complex_number_problems

This tutorial goes through a fancy problem from the IIT JEE exam in India (competitive exam for getting into their top engineering schools). Whether or not you live in India, this is a good example to test whether you are a complex number rock star.

Complex_conjugates_dividing_complex_numbers

Learn how to divide complex numbers using the conjugate of the divisor. For example, divide (2+3i) by (-1+4i) by multiplying both the dividend and the divisor by (-1-4i).

Multiplying_complex_numbers

Learn how to multiply complex numbers using the fact that i^2=-1 and the distributive property. For example, multiply (1+i) by (2+3i).

Distance_midpoint_of_complex_numbers

Learn how we define the distance of two complex numbers, and how we define their midpoint.

What_are_the_imaginary_numbers_

Learn about the imaginary unit i (which is the square root of -1) and about imaginary numbers like 3i (which is the square root of -9).

What_are_the_complex_numbers_

Learn about complex numbers (spoiler: they are numbers that consist of both real and imaginary parts).

Multiplying_dividing_complex_numbers_in_polar_form

Learn how complex multiplication and division work when the numbers are given in polar form. Amazingly enough, this is much easier then multiplication and division in rectangular form.

Absolute_value_angle_of_complex_numbers

Learn about very important graphical features of complex numbers: their absolute value and their angle.

The_complex_plane

Learn how we can visualize complex numbers in a plane. This can be seen as an expansion of the 1-dimensional real number line into a 2-dimensional plane!

Polar_form_of_complex_numbers

Learn how to represent complex numbers in a different way. Unlike rectangular form, which emphasizes the real and imaginary parts, polar form emphasizes the absolute value ("modulus") and the angle ("argument").

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