问题:证明:E(X-c)2当c=E(X)时取得最小值D(X)....
Thursday, September 22, 2022
问题:求出两多项式函数P(x)、Q(x),使得下面等式成立: ∫[(2x4-1)cosx+(8x3-x2-1)sinx]dx...
Thursday, September 22, 2022
问题:设f有二阶偏导数,z=f(xy),则∂2z/∂x∂y等于( )。...
Thursday, September 22, 2022
问题:问答题设f′(x)在[a,b]上连续,在(a,b)内可导,且f(a)f(b)>0,f(a)f[(a+b)/2]<0,试证至少存在一个点ξ∈(a,b)使f′(ξ)=f(ξ)。...
Thursday, March 30, 2023
问题:设y=y(x)满足∫ydx·∫(1/y)dx=-1,且当x→+∞时y→0,y(0)=1,则y=____。...
Thursday, September 22, 2022
问题:设试验E有4个基本事件,即s={w1,w2,w3,w4},并且它们发生是等可能的,又设A1={w1,w2},A2={w1...
Wednesday, September 21, 2022
问题:问答题事件A与B互不相容,且0<P(B)<1,证明:P(A|B(_))=P(A)/(1-P(B))。...
Friday, December 1, 2023
问题:设P(A)=0.4,P(B)=0.3,P(A∪B)=0.6,则P(AB(_))=____。...
Thursday, September 22, 2022
问题:设函数f(x)在(a,b)内连续,a<x1<x2<…<xn<b,证明:必∃ξ∈(a,b),使f(ξ)=[f(x1)+f(...
Monday, September 19, 2022
问题:设a(→),b(→)为非零向量,且a(→)⊥b(→),则必有( )。...
Thursday, September 22, 2022
问题:设a(→),b(→)为非零向量,且a(→)⊥b(→),则必有( )。...
Thursday, September 22, 2022
问题:设函数y=1/(2x+3),则y(n)(0)=____。...
Monday, September 19, 2022
问题:在区间(-∞,+∞)内方程|x|1/4+|x|1/2-cosx=0( )。...
Wednesday, September 14, 2022
问题:若向量X(→)与向量α(→)={2,-1,2}共线,且满足方程α(→)·X(→)=-18,则X(→)=____。...
Thursday, September 22, 2022
问题:问答题求过点M(-1,0,1)且垂直于直线(x-2)/3=(y+1)/(-4)=z/1又与直线(x+1)/1=(y-3)/1=z/2相交的直线方程。...
Thursday, September 21, 2023
问题:若物体的运动规律为s=3sin2t,则其在t=0时的速度等于____,加速度为____。...
Thursday, September 22, 2022