y=log2底sin(2x+π/4)有意义sin(2x+π/4)＞0单增区间为2kπ＜2x+π/4＜2kπ+π/22kπ-π/4＜2x＜2kπ+π/2-π/4kπ-π/8＜x＜kπ+π/8单减区间为2kπ+π/2＜2x+π/4＜2kπ+π2kπ+π/2-π/4＜2x＜2kπ+π-π/4kπ+π/4＜x＜kπ+3π/8
