  We show that the factorial flagged Grothendieck polynomials defined by
flagged set-valued tableaux of Knutson-Miller-Yong can be expressed by a
Jacobi-Trudi type determinant formula, generalizing the work of
Hudson-Matsumura. In particular, we obtain an alternative proof of the tableau
and determinant formulas of vexillary double Grothendieck polynomials, that
have been obtained by Knutson-Miller-Yong and Hudson-Matsumura respectively.
Moreover, we show that each factorial flagged Grothendieck polynomial can be
obtained from a product of linear polynomials by applying K-theoretic divided
difference operators.
