Let (2 + √3) be rational.
Then, both (2 + √3) and 2 are rational.
∴ { (2 + √3) – 2 } is rational [∵ Difference of two rational is rational]
⇒ √3 is rational.
This contradicts the fact that √3 is irrational.
The contradiction arises by assuming (2 + √3) is rational.
Hence, (2 + √3) is irrational.