原式=[1+2^(-1/8)]*[1+2^(-1/4)]*[1+2^(-1/2)]
=[1-2^(-1/8)]*[1+2^(-1/8)]*[1+2^(-1/4)]*[1+2^(-1/2)]/[1-2^(-1/8)]
=[1-2^(-1/4)]*[1+2^(-1/4)]*[1+2^(-1/2)]/[1-2^(-1/8)]
=[1-2^(-1/2)]*[1+2^(-1/2)]/[1-2^(-1/8)]
=(1-1/2)/[1-2^(-1/8)]
=(1/2)/[1-2^(-1/8)]
=1/[2-2^(7/8)]