证明:当 gt 0 时,有不等式 arctan x+dfrac (1)(x)gt dfrac (pi )(2)

证明下列不等式:-|||-(4)当 lt xlt dfrac (pi )(2) 时, tan xgt x+dfrac (1)(3)(x)^3 ;

[题目]解不等式: dfrac (x-1)(x+1)gt 0 -

证明:当 lt xlt dfrac (pi )(2) 时, tan xgt x+dfrac (1)(3)(x)^3.

、证明:当 -1lt xlt 0 时, arcsin sqrt (1-{x)^2}-arctan dfrac (x)(sqrt {1-{x)^2}}=dfrac

5.证明下列不等式:-|||-(3)当 lt xlt dfrac (pi )(2) 时, sin x+tan xgt 2x ;

解不等式：dfrac (1)(x)lt 2dfrac (1)(x)lt 2 解不等式：

证明下列不等式: (1)|arctan a-arctan b|≤|a-b|; (2)当x>1时, ex>ex证明下列不等式: (1)|arctan

设(X,Y)的分布函数为(x,y)=dfrac (1)({pi )^2}(dfrac (pi )(2)+arctan dfrac (x)(2))(dfrac (

证明等式 arctan x=arcsin dfrac (x)(sqrt {1+{x)^2}} , in (-infty ,+infty

[题目]证明:当 gt 1 时, ^x-1gt dfrac (1)(2)(x)^2+dfrac (1)(2)