Take the two vectors that are inside the norms on the right.
So you have two vectors or two kets.
Do the inner product of these two kets. One ket becomes a bra. And you write the bracket of the bra and ket.
You should then recognise the left hand side.
So you have two vectors or two kets.
Do the inner product of these two kets. One ket becomes a bra. And you write the bracket of the bra and ket.
You should then recognise the left hand side.
