若log2/1(sin a)+log2/1(sin b)=2,(27^cos a)^cos b=1/9,cos(2a+2b)=?

若log2/1(sin a)+log2/1(sin b)=2,(27^cos a)^cos b=1/9,cos(2a+2b)=? 若a属于【0,π/4】,y=log2(1+cos（9/2π-a）)+log2(1+sin（a-5π）)的值域为 若log2(a)*log2(b)=1 (a>1,b>1),则ab的最小值为 若log2 a>1,b>1,log2（a）*log2（b）=64,求log2(ab)最小值 log2(log2 log2(3)×log2(4)=log2(7)?log2(3)×log2(4)=log2(7)吗?log2(1/49)+log2(1/16)+log2(1/27)等于多少呢?帮个忙! log2底sin(3π-a)=-2,且tana 若x∈(0,1] 不等式f(x)≥log2（4^x-1)+log2(a/4^x)-ax恒成立 log2 SQR(7/48)+log2 12 -1/2log2 42 log2 SQR(7/48)+log2 12 -1/2log2 48 集合A｛x|log2(x+1) 已知a=2,求log2 1 设a>1,b>1,log2(a)×log2(b)=1.则log2(ab)的最小值为多少为什么log2(a)＞0？ |[log2(x)]^2-3log2(x)+1| log2(x+1)>log2(3-x) log2 (x+1)+log2 x=log6 (log2)2+log2*log50+1g25值