### Prove that  1√11   is an irrational number.

Step by Step Explanation:
1. Let's assume
 1 √11
is a rational number.
Therefore, we can find two integers, a and b, such that,

 1 √11
=
 a b
[where, b is not equal to zero.]
2. Now,
√11 =
 b a

 b a
is a rational number as a and b are integers.
Therefore, √11 is a rational which contradicts to the fact that √11 is Irrational.
Hence, our assumption is false and
 1 √11
is irrational.
3. Therefore,
 1 √11
is an irrational number.