Simplify: \gb2x\g_{b^2} x\gb2x in terms of \gbx\g_b x\gbx.
\ac12\gbx\ac{1}{2}\g_b x\ac12\gbx
2\gbx2\g_b x2\gbx
\gb(x/2)\g_b (x/2)\gb(x/2)
(\gbx)2(\g_b x)^2(\gbx)2