定义域:
{x|2k*pi-arccos((3+33^(1/2))/4)+2k*pi}k是整数
-cos2x+3cosx+2=-2cos^2+3cosx+3>0
即:-2(cosx-3/4)^2+33/8>0
cosx>(3+33^(1/2))/4
2k*pi-arccos((3+33^(1/2))/4)+2k*pi,k是整数
值域:
(-∞,log2(33/8))
0
定义域:
{x|2k*pi-arccos((3+33^(1/2))/4)+2k*pi}k是整数
-cos2x+3cosx+2=-2cos^2+3cosx+3>0
即:-2(cosx-3/4)^2+33/8>0
cosx>(3+33^(1/2))/4
2k*pi-arccos((3+33^(1/2))/4)+2k*pi,k是整数
值域:
(-∞,log2(33/8))
0