log1/2(x＋1)
=[log2(x＋1)]/log2(1/2)
=[log2(x＋1)]/log2(2＾－1)
=－log2(x＋1)
=log2(x＋1)＾(－1)
=log2[1/(x＋1)]
∴log1/2(x＋1)≥log2(2x＋1)
=>log2[1/(x＋1)]≥log2(2x＋1)
∴
{1/(x＋1)≥2x＋1
{x＋1>0
{2x＋1>0
解出－1/2