Question

prove that 5√2 irrational

Answer 1

let us assume 5 root 2 is a rational
Then,5 root 2 =a/b
            root 2 =a/b-5
Since a and b are integers a/b-5 is rational,but this contradicts to the fact root 2 is irrational , so our initial assumption is wrong.
 Therefore 5 root 2 is irrational
     Hence proved