Question

Prove that 3a^ 2 -1 is never a perfect square

Answer 1

let a=1
3(1)^2 -1
3-1 =2
2 is not a perfect square
let a =3
3(3)^2-1
3(9)-1
27-1 =26
it is not a perfect square

similarly explain by taking 1or 2 more value of a.