【判断题】Both air way bill and sea way bill are not documents of title.( )
【单选题】Both Bill and Mary produce t-shirts and hats. If Bill’s opportunity cost of 1 t-shirt is 4 hats and Mary’s opportunity cost of 1 t-shirt is 3 hats, then
A.
Bill has a comparative advantage in the production of t-shirts.
B.
Mary has a comparative advantage in the production of t-shirts.
C.
Mary has a comparative advantage in the production of hats.
D.
Bill has a comparative advantage in the production of both t-shirts and hats.
【单选题】已知函数f(x)=x 3 -3ax 2 +2bx在点x=1处有极小值-1,则a,b的值分别为( )
【单选题】已知函数f(x)=x 3 +ax 2 +bx+c,x∈[-2,2]表示的曲线过原点,且在x=±1处的切线斜率均为-1,有以下命题: ①f(x)的解析式为:f(x)=x 3 -4x,x∈[-2,2]; ②f(x)的极值点有且仅有一个; ③f(x)的最大值与最小值之和等于零,则下列选项正确的是( )
【单选题】已知函数 在点 处有二阶导数,且 ,则下列结论正确的是( )
【单选题】已知f(x)=ax 3 -x 2 -x-1在x 0 =1处有极小值,则a的值为( )
【单选题】已知 在 处有极小值,则a 的值为( ).