Khan Academy: Algebra: Complex Numbers: Multiplying Complex Numbers

Video shows working a problem from the IIT JEE test which involves using algebraic manipulation to determine the validity of an equation with magnitudes of the differences of certain complex numbers. [7:21]

Video shows working a problem from the IIT JEE test which involves algebraic manipulation and using what the argument of complex numbers is to visually reason if two given equations about arguments are true. [7:26]

Video shows working a problem from the IIT JEE test which involves determining whether the determinant of a matrix of four given complex numbers is 0. [3:09]

Video shows an example of subtracting complex numbers. [1:53]

Video shows an example of dividing complex numbers using complex conjugates. [4:58]

Video shows how to use the quadratic formula to find roots of a quadratic equation in a situation where the roots are complex. Includes showing how to verify the answers are correct solutions of the quadratic. [10:15]

Video shows an example of adding complex numbers. Includes link to additional practice problems. [1:11]

Video first reviews what natural numbers, whole numbers, integers, rational numbers, irrational numbers and real numbers are. Gives examples of classifying numbers. [5:17]

Video shows how to write i raised to various powers as simpler problems using exponent rules and the simple powers of i rules shown in the previous video. Includes link to additional practice problems. [6:20]

Video shows the logic behind why some believe that saying i is the principal root of -1 is wrong. Explains why the logic is faulty. Explains more technically the meaning of principal root. [6:44]