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

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

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

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

[题目]-|||-证明:当 lt xlt dfrac (pi )(2) 时, sin x+tan xgt 2x

设(x)=((2-x))^tan dfrac (pi {2)x},(dfrac (1)(2)lt xlt 1),求(x)=((2-x))^tan dfrac (

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

下面哪个方程在 [ 0 , 1 ] 内有实根A.+tan x+dfrac (1)(4)=0A.+tan x+dfrac (1)(4)=0A.+tan x+dfr

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

(8) lim _(xarrow dfrac {pi )(2)}dfrac (tan x)(tan 3x)

(8) lim _(xarrow dfrac {pi )(2)}dfrac (tan x)(tan 3x)