3.两抛物线 =2(x)^2 , =3-(x)^2 及x轴所围成的封闭图形为D,求:-|||-(1)平面图形D的面积;-|||-(2)平面图形D绕y轴旋转一周所形成的几何体的体积.

(19) (本题满分12分)已知y(x)满足x^2y^n+xy'-9y=0,满足y(1)=2,y'(1)=6(1)利用变换x=e^t将上述方程化为常系数线性方程，并求y(x);(2)计算int_(1)^2y(x)sqrt(4-x^2)dx

解答题:-|||-函数 f(x)= { ,xgt 0, ax+b,xleqslant 0 . 在 x=0 处可导,试求常数a,b.

下列各题中,哪些数列收敛,哪些数列发散?对收敛数列,通过观察(xn)的变化-|||-趋势,写出它们的极限:-|||-(5) n{(-1))^n} ;-|||-(6) dfrac {{2)^n-1}({3)^n}} -|||-(7) n-dfrac {1)(n)} ;-|||-(8) [ {(-1))^n+1] dfrac (n+1)(n)}

当theta =dfrac (pi )(3)时，theta =dfrac (pi )(3)______，theta =dfrac (pi )(3)______，theta =dfrac (pi )(3)______.

(4)设函数 f(x)= ) -1,|x|gt 1 1,|x|leqslant 1 . ,求f (f(x )。。

3.证明:如果向量a.b共线,那么向量 2a+b 与a共线.-|||-4.如图,已知四面体ABCD的所有棱长都等于a,E,F,G分别是-|||-棱AB,AD,DC的中点.求:-|||-(1)AB·AC;-|||-(2)→(AD)·→(DB);-|||-(3)→(GF)·→(AC);-|||-(4) →(EF)·→(BC)-|||-(5)→GG·→BA;-|||-(6)→(GE)·→(GF)-|||-F-|||-B D-|||-G-|||-C

[题目]如图,连续函数 y=f(x) 在区间 [-3,-2], 2,3]-|||-上的图形分别是直径为1的上、下半圆周,在区间-|||-[ -2,0] , [0,2]的图形分别是直径为2的下、上半圆周,-|||-设(x)=(int )_(0)^xf(t)dt, 则下列结论正确的是 ()-|||-3-2 2 方 x-|||-A. (3)=-dfrac (3)(4)F(-2)-|||-B. (3)=dfrac (5)(4)F(2)-|||-C. (3)=dfrac (3)(4)F(2)-|||-D. (3)=-dfrac (5)(4)F(-2)

453设数列(xn)满足 _(1)=1, _(n+1)=dfrac ({x)_(n)+2}({x)_(n)+1}(n=1,2,... ) 试证 lim (x)_(n)=sqrt (2).

[题目]若-|||-=(int )_(0)^2(x)^2dx =(int )_(0)^2(x)^3dx, =(int )_(0)^2sin xdx, 则a,b,c大-|||-小关系是() ()-|||-A. lt clt b-|||-B. lt blt c-|||-C. lt blt a-|||-D. lt alt b

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