Khan Academy: Complex Numbers: Complex Numbers (Part 1)

If the square root of negative one exists, where is it on the number line? A math video presents a geometric representation of complex numbers and the complex plane, and then compares it to the geometric representation of real...

This video continues looking at dividing complex numbers by looking at the conjugate of a complex number. The instructor then uses the conjugate to rationalize the denominator of a rational expression with a complex number in the...

Sal discusses the usefulness of the conjugate of the complex number in this video. First, he shows how to add a complex number and its conjugate graphically and algebraically. Then, he shows how to simplify a rational expression with...

In this video, a complex number is defined and graphed on the complex plane. Sal also shows how to add, subtract, and multiply two complex numbers. He shows how to divide two complex numbers but runs out of time and continues in the...

Students are always fascinated by imaginary numbers. In this video, Sal defines the imaginary unit, i, and shows when raising i to an exponent, it has a cyclic nature.

In this video, a complex number is defined and graphed on the complex plane. Sal also shows how to add, subtract, and multiply two complex numbers. He shows how to divide two complex numbers but runs out of time and continues in the...

Sal solves a complex determinant problem from the 2010 IIT entrance test. Knowledge of determinants, the exponential form of complex numbers, trigonometric ratios, and algebraic thinking are all utilized here.

Dividing complex numbers. Complex conjugates.

The video lesson from Khan Academy provides practice questions for the SAT. Watch Sal work through a basic Complex numbers problem.

The video lesson from Khan Academy provides practice questions for the SAT. Watch Sal work through a harder complex numbers problem.