Question

Which of the following is irrational?

Options

• \[\sqrt{\frac{4}{9}}\]

• \[\sqrt{\frac{4}{5}}\]

• \[\sqrt{7}\]

• \[\sqrt{81}\]

Answer 1

Given that

`sqrt4/9 = 2/3`

`4/5 = 0.8`

`sqrt81  9`

And 7 is not a perfect square.