By folding an isosceles right triangle in half, its new linear dimension is $1/\sqrt2$ of its original dimension. If the electrical potential energy of the original charged triangle is $U$, then the potential energy of the new triangle is $\sqrt2U$, because potential energy varies inversely with distance while the total charge remains the same. Thus, the work done in the first folding is $A=\sqrt2U-U$. If the new triangle is folded once more, then the potential energy of the last triangle is $(\sqrt2)^2U$, and the work done in the second folding is $(\sqrt2)^U-\sqrt2U=\sqrt2A$.