当X等于多少时,(tan^2x-tanx+1)/(tan^2x+tanx+1)有最大值?

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当X等于多少时,(tan^2x-tanx+1)/(tan^2x+tanx+1)有最大值?当X等于多少时,(tan^2x-tanx+1)/(tan^2x+tanx+1)有最大值?当X等于多少时,(tan

当X等于多少时,(tan^2x-tanx+1)/(tan^2x+tanx+1)有最大值?
当X等于多少时,(tan^2x-tanx+1)/(tan^2x+tanx+1)有最大值?

当X等于多少时,(tan^2x-tanx+1)/(tan^2x+tanx+1)有最大值?
令a=tanx,a属于R
y=(a^2-a+1)/(a^2+a+1)
ya^2+ya+y=a^2-a+1
(y-1)a^2+(y+1)a+(y-1)=0
判别式大于等于0
(y+1)^2-4(y-1)^2>=0
(y+1+2y-2)(y+1-2y+2)>=0
(3y-1)(-y+3)>=0
(3y-1)(y-3)