【单选题】y=f(x)=sinx,x(t)=t 2 ,d 2 y=()。 A. (2cost 2 -4t 2 sint 2 )dt 2 B. (2cost 2 +4t 2 sint 2 )dt 2 C. (cost 2 -4t 2 sint 2 )dt 2 D. (cost 2 +4t 2 sint 2 )dt 2

设向量函数A（t）=2cost，sint，t），则导数向量为（）。 A: -2sint，cost，1 B: 2sint，cost，1 C: -2sint，sint，1 D: -2cost，sint，1

(cost）^4*(sint)^2+(cost）^2*(sint)^4如何化简为(cost）^2*(sint)^2?麻烦告诉下,

The total annual cost is the sum of annual material cost, annual order cost, and annual holding cost, and is given as TC = CD + (D/Q)S + (Q/2)hC.

以下合法的变量名是（）。 A: A%B B: Test1 C: 2cost D: And

在RIP路由协议进程中设定默认度量值为2的命令是( ) A: [H3C-rip-1]default 2 B: [H3C-rip-1]default cost 2 C: [H3C]default cost 2 D: [H3C]default 2

Fixed Cost，Veriable Cost，Explicit Cost，Implicit Cost，Opportunity Cost，Sunk Cost，Economic Profit，Normal Profit，Average Cost，Margial Cost

Three cost drivers are used to estimate the cost of processing insurance claims. The cost drivers are: (1) claim amount, (2) age of vehicle in accident and (3) age of driver in accident. The percentages attributable to the cost drivers are 50% for claim amount, and 15% for each of the other two cost drivers. What is the cost to process Claim #101? The claim amount is $1,000. The age of the vehicle is 5 years. The age of the driver is 20 years.

图示单口网络的端口电压u(t)=2cost V，则电压uC等于__。 【图片】

求下列曲线段的长度,曲线段y=∫(-π/2,x)(cost)^(1/2)dt