已选分类
理学数学
单选题
单选题极限
单选题设A，B均是n阶可逆矩阵,则为______。A.(-2)n丨A丨丨B丨-1B.-2丨AT丨丨B丨C.-2丨A丨丨B-1丨D.(-2)2n丨A丨丨B丨-1
单选题
单选题设随机变量X与Y相互独立，且方差DX＞0，DY＞0，则
A．X与X+Y一定相关． B．X与X+Y一定不相关．
(c)X与XY一定相关． D．X与XY一定不相关．
单选题
单选题，则f(x)=______
单选题
单选题二元函数f(x，y)在点(0，0)处可微的一个充分条件是A．B．C．D．
单选题当x→0时，x
2
是e
tanx
-e
x
的_______
单选题极限等于______．A．0B．C．D．1
单选题
单选题以下3个分式方程的所有解之积为______。A．B．C．D．
单选题
单选题
单选题
单选题若3(a
2
+b
2
+c
2
)=(a+b+c)
2
，则a，b，C三者的关系为( )．
单选题
单选题
单选题John budgeted 50% of his take-home pay for household expense, 20% for transportation, 15% for a retirement fund, and the remaining $240 for recreation. How much of his take home pay did he budget for household expenses?