Question

Prove that 32root5 is irrational.

Answer 1

let 3 + 2 root 5 is rational 
therefore 3 + 2 root 5=a/b 
root 5=a-3/2b 
because  a-3/2b is rational 
therefore root 5 will also be rational 
but we know that, 
root 5 is irrational 
that is our supposition is wrong 
that is 3+2 root 5 is irrational.........

hope its help u.......