(b) Circle the expressions below that correspond to valid inner products on R2. (x, y) =y Qx, Q= HO (a, y) = max (X191, X242) (ac , y) = y Qx, Q= 1 5 ( a, y) = y Qx, Q= (x, y) = y Qx, Q- (Recall that we can expand y Qx = Q1,12191 +21,242917@2,12192 +Q2,20242, where the Qij are the entries of Q and the ri, yi are the entries of x, y. )