# Green function derived from the idea of position representation in quantum mechanics

I am trying to study green's function by using a lecture by NPTEL its link is https://www.youtube.com/watch?v=ZJ7v6VZQ32k&t=439s I don't get this step by him at the minute of ten.

$$D_x G(x,x^{'}) =\langle x|x'\rangle =\delta (x-x').$$

• Are you asking about the first or second equality? – Qmechanic Jun 5 at 8:46
• first equality, – Robin Raj Jun 5 at 9:01
• What do you think is missing in Prof. Balakrishnan's argument? – Qmechanic Jun 5 at 10:35
• I don't get how position representation of some operator operates on position representation of inverse of that operator gives inner product of x with x' – Robin Raj Jun 5 at 17:39
• An operator times its inverse yields the identity, which, in the position representation, is visibly the position delta function, no? – Cosmas Zachos Jun 6 at 0:31