√((sinx)^6+(cosx)^6+asinxcosx)定义域为R求a的范围

根号下=>0
有：（1-cos^2）^3+cos^6+asincos=>0
1+3cos^4-3cos^2+asincos=>0
1+3(cos^2)(cos^2-1)+asincos>=0
1-3(sincos)^2+asincos=>0
-1+3(sincos)^2-asincos<=0
sincos的值域：
sincos=0.5sin2x即[-0.5,0.5]
设M=sincos
3(M-a/6)^2<=1+a^2/12
式子-1+3M^2-aM<=0在M=-0.5,0.5,a/6要求全部成立（如果a/6在[-0.5,0.5]外可以不计算a/6这一点）

-0.5:a<=0.5
0.5:a >=-0.5
a/6：永远成立

所以：a值域：[-0.5,0.5]