The values of x for which the angle between the vectors $\overline{\mathrm{a}} = \mathrm{x}\overline{\mathrm{i}}- 3 \overline{\mathrm{j}}-\overline{\mathrm{k}}$ and $\overline{\mathrm{b}} = 2\mathrm{x}\overline{\mathrm{i}} + \mathrm{x}\overline{\mathrm{j}} - \overline{\mathrm{k}}$ is acute, and the angle between the vector $\overline{\mathrm{b}}$ and the axis of ordinates is obtuse, are