1、曲线 =3(x)^4-4(x)^3+1 的凸区间是 () ;-|||-(A) (-infty ,0) (B) (1,+infty ) (C) (dfrac (2)(3),+infty ) (D) (0,dfrac (2)(3))

20、曲线y=x^3-x^2+3x+2的上凸区间为B、(-infty,(1)/(3)) C、(-infty,3) D、((1)/(3),+infty) E

(4) (x)=(x)^3-(x)^2-x+1 满足 () .-|||-(A)在 (-infty ,-dfrac (1)(3)] 内单调递增 (B)在 [ d

(int )_(-infty )^+infty (x)^2(e)^-a(x^2)dx=dfrac (1)(2)sqrt (dfrac {pi )({a)^3}}

计算(int )_(0)^+infty dfrac (dx)({x)^2+4x+3}的值是A (int )_(0)^+infty dfrac (dx)({x)^

4.下列结论正确的是 ()-|||-(A) (int )_(-infty )^+infty dfrac (x)(1+{x)^2}dx=0 (B) (int )_

[题目]函数 (x)=(x)^2+4x-1 的单调增加区间是-|||-()-|||-A、 (-infty ,2)-|||-B、 (-1,1)-|||-C、 (2

4.求下列极限:-|||-(1) lim _(xarrow infty )(e)^dfrac (1{x)} :-|||-x→∞-|||-(3) lim _(xa

讨论 (x)=dfrac (1)(x) 在区间(0,1),(1,2), (2,+infty ) (0,+infty ) 上的有界性.

17、单选 lim _(xarrow infty )dfrac (sin 3x+2x)(sin 2x-3x)-|||-A dfrac (1)(3)-|||-B

[题目]-|||-求曲线 =3(x)^4-4(x)^3+1 的拐点及凹凸区间.