\[2x + 6,\ \ x + 7,\ \ x + 4\]
\[(x + 7)^{2} = (2x + 6)(x + 4)\]
\[x^{2} + 14x + 49 = 2x^{2} + 8x + 6x + 24\]
\[x^{2} = 25\]
\[x = \pm 5.\]
\[при\ x = 5 \Longrightarrow 16;12;9;\]
\[при\ \ x = - 5 \Longrightarrow - 4;2;\ - 1.\]
\[Ответ:16;12;9\ \ \ \ или\ \ - 4;\ 2;\ - 1.\]