I need your help on how to show the existence of a bialgebra pairing: for the polynomial ring $K[x]$ and$k[x]$ over a field $x \in P(K[x])$$k$, there is a bialgebra pairing $t: K[x] \times K[x] \to k$$t:k[x]\otimes k[x]→k$ such that $t(x,x)=1$. What is the unique bialgebra pairing satisfying $t(x,x)=1$?