Khan Academy

Proof: √2 is irrational (K-A)

Proof: square roots of prime numbers are irrational (K-A)

Proof: there's an irrational number between any two rational numbers (K-A)

Proof: product of rational & irrational is irrational (K-A)

Proof: sum & product of two rationals is rational (K-A)

Proof: sum of rational & irrational is irrational (K-A)

Sums and products of irrational numbers (K-A)

Worked example: rational vs. irrational expressions (K-A)

Worked example: rational vs. irrational expressions (unknowns) (K-A)

Adding complex numbers (K-A)

Subtracting complex numbers (K-A)

Complex number operations review (K-A)

Multiplying complex numbers Notes (K-A)

Multiplying complex numbers Video (K-A)

Plotting numbers on the complex plane (K-A)

The complex plane Notes (K-A)

Intro to complex numbers Notes (K-A)

Intro to complex numbers Video (K-A)

i as the principal root of -1 (K-A)

Intro to the imaginary numbers Notes (K-A)

Intro to the imaginary numbers Video (K-A)

Powers of the imaginary unit Notes (K-A)

Powers of the imaginary unit Video (K-A)

Simplifying roots of negative numbers (K-A)

Interpreting change in exponential models: changing units (K-A)