[tex]The\ value\ of\ the\ square\ pyramid:V=\dfrac{1}{3}BH\\\\B=128in^3;\ H=6in\\\\subtitute:\\\\\dfrac{1}{3}B\cdot6=128\\\\2B=128\ \ \ |divide\ both\ sides\ by\ 2\\\\B=64\ (in)\\\\a-the\ length\ of\ the\ base\\\\B=a^2\\\\a^2=64\to a=\sqrt{64}\to\boxed{a=8\ (in)}[/tex]
