定积分 ^2-dfrac (1)(x)+C ()()-|||-A dfrac (1)(2)(x)^2+dfrac (1)(x)+C-|||-B dfrac (1)(2)(x)^2-dfrac (1)(x)+C-|||-C int dfrac (cos x)(2+)dx=

lim _(xarrow infty )(2-dfrac (1)(x)+dfrac (1)({x)^2});;

(B) dfrac (1)(2)(X)_(1)+dfrac (1)(2)(X)_(2)-|||-(C) dfrac (1)(2)(X)_(1)+dfrac (1

【题文】已知(x+dfrac (1)(x))=(x)^2+dfrac (1)({x)^2}，求(x+dfrac (1)(x))=(x)^2+dfrac (1)(

f(x)= ({e)^4-dfrac (1)(3))-|||-dfrac (1)(2)(e)^4-|||-dfrac (1)(2)((e)^2-dfrac

(B) dfrac (1)(2)(X)^2+dfrac (1)(2)(Y)^2 服从x^2分布.-|||-(C) dfrac (1)(3)((X+Y))^2 服

[题目]若 (dfrac (1)(x))=x, 则 (x)= ()-|||-A、 dfrac (1)(x)-|||-B、 dfrac (1)({x)^2}-||

(1)已知 (x+dfrac (1)(x))=(x)^2+dfrac (1)({x)^2}, 则 f(x)= __ ;

dfrac (1)(x) C. -dfrac (1)({x)^2} D. dfrac (2)({x)^3}

4.计算下列极限(10)lim _(xarrow infty )(1+dfrac (1)(x))(2-dfrac (1)({x)^2})4.计算下列极限(10)

dfrac (1)(5)(X)_(1)+dfrac (2)(5)(X)_(2)+dfrac (2)(5)(X)_(3)-|||-D .dfrac (1)(7)(