Question

Which of these numbers are irrational: `47, \sqrt 0.09, \sqrt 15, 8/45`?

Answer 1

only `sqrt15` is irrational

Explanation:

`47=47/1 => 47 in QQ`

`sqrt(0.09)=sqrt(9/100)=3/10 => sqrt(0.09) in QQ`

`sqrt(15)=sqrt(5*3)`
5 and 3 are primes
`=> sqrt15 notin QQ`

`8/45 => 8/45 in QQ`