RU-ALLRUSSIAN 1984 Problem 19

The real sequence $\mathbf{x}_{\mathrm{n}}$ is defined by $\mathbf{x}_{1} = 1$ $\mathbf{x}_{2} = 1$ $\mathbf{x}_{\mathrm{n} + 2} = \mathbf{x}_{\mathrm{n} + 1}{}^{2} - \mathbf{x}_{\mathrm{n}} / 2$ . Show that the sequence converges and find the limit.