see, the definition of irrational number says that the no should be non terminating non repeating (like 1.333)

so first we need to find decimal values of 5/7 and 9/11

5/7= 0.714285.. and 9/11= 0.8181...

therefore three irrational no are

1- 0.72722722272222.....

2- 0.78788788878888.....

3- 0.80800800080000...

(basically, try to establish a pattern) :)