Three point charges + q,-2 q and +q are placed along x -axis at points x=-1 m, x=0 m and x=2 m respectively. The potential energy of the system is

Three point charges $\displaystyle +\mathrm{q},-2 \mathrm{q}$ and +q are placed along $\displaystyle x$-axis at points $\displaystyle x=-1 \mathrm{~m}, x=0 \mathrm{~m}$ and $\displaystyle x=2 \mathrm{~m}$ respectively. The potential energy of the system is