Let 1/√2 is rational.
Therefore, we can find two co-prime integers a, b (b ≠ 0) such that
1/√2 = a/b
Or
√2 = b/a
b/a is as a and b are integers.
Therefore, √2 is rational which contradicts to the fact that √2 is irrational.
Hence, our assumption is false and 1/√2 is irrational.

Video Explanation😀