Proof by Contradiction [IB Math AA HL]

The speaker explains the concept of proof by contradiction using the example of proving that the square root of 2 is irrational. The process involves assuming the opposite (that root 2 is rational and can be expressed as a/b where a and b have no common factors), then demonstrating that this assumption leads to a contradiction (both a and b must be even, meaning they share a common factor of 2). This contradiction invalidates the initial assumption, thereby proving the original statement that root 2 is irrational.