A.2(2x2-x+1)(4x-1)
B.(2x2-x+1)(4x-1)
C.(2x2-x+1)(4x+1)
D.(2x2+x+1)(4x-1)
[单选题]|y-a|≤2成立.()(1)|2x-a|≤1(2)|2x-y|≤1A.条件(1)充分,但条件(2)不充分B.条件(2)充分,但条件(1)不充分C.条
[单选题]|y-a|≤2成立.()(1)|2x-a|≤1(2)|2x-y|≤1A.条件(1)充分,但条件(2)不充分B.条件(2)充分,但条件(1)不充分C.条
[单选题]|y-a|≤2成立.()(1)|2x-a|≤1(2)|2x-y|≤1A.条件(1)充分,但条件(2)不充分B.条件(2)充分,但条件(1)不充分C.条
[单选题]|y-a|≤2成立.()(1)|2x-a|≤1(2)|2x-y|≤1A.条件(1)充分,但条件(2)不充分B.条件(2)充分,但条件(1)不充分C.条
[问答题]f(x)=x2,则f′(x)在x=2处的导数值为__________。
[单选题]若集合M={0,1,2},N={(x,y)x-2y+1≥0且x-2y-1≤0,x,y∈M},则N中元素的个数为()A . 9B . 6C . 4D . 2
[问答题]设X1,X2,Y均为随机变量,已知Cov(X1,Y)=-2,Cov(X2,Y)=5,则Cov(X1+X2,Y)=().
[单选题]设f(x)具有二阶导数,y=f(x2),则的值为()。A . f"(4)B . 16f"(4)C . 2f'(4)+16f"(4)D . 2f'(4)+4f"(4)
[单选题]已知函数的全微分df(x,y)=(3x2+4xy-y2+1)dx+(2x2-2xy+3y2-1)dy,则f(x,y)等于( ).A.B.C.D.
[单选题]已知函数的全微分df(x,y)=(3x2+4xy-y2+1)dx+(2x2-2xy+3y2-1)dy,则f(x,y)等于( ).A.B.C.D.