Question

prove that (3- root 7)power 2 ia a irrational no

Answer 1

[3-root7]power2
by using [a-b]power 2 identity
9-7+6root7
2+6root7
let 2+6root7=rational
2+6root7=p/q
2=p/q-6root7\
2q/p=-6root7
2q/-6p=root7
1q/-3p=root7
since root 7 is irrational 
then 1q/-3p is also irrational 
therefore 2+6root7 is irrational