(1) | ![]() |
Assume ![]() |
(2) | GCD(P,Q)=1 | P/Q is expressed in lowest terms |
(3) | Q2 = 2·P2 | Square both sides & multiply by Q2 |
(4) | Q = 2·R | Both sides must be divisible by 2 |
(5) | (2·R)2 = 2·P2 | Substituting |
(6) | 4·R2 = 2·P2 | Expanding |
(7) | 2·R2 = P2 | Divide both sides by 2. |
(8) | P = 2·S | Both sides must be divisible by 2. |
(9) | GCD(P,Q)=2 | Both P and Q divisible by 2. |
(10) | ![]() ![]() |
By reductio ![]() |