Let us assume that 3√3 be a rational number.
Then, it will be of the form a/b where a and b are co-prime and b≠0.
Now, a/b =3√3
a/3b = √3
Since, a is an integer and 3b is also an integer (3b ≠ 0)
So, a/3b is a rational number
√3 is a rational number
But this contradicts to the fact that √3 is an irrational number.
Therefore, our assumption is wrong.
Hence, 3√3 is an irrational number.