1.Find the dimensions of the largest rectangle that can be inscribed in the semicircle y=√4-x平方.

1.Find the dimensions of the largest rectangle that can be inscribed in the semicircle y=√4-x平方.
2.a closed cylindrical can is to have a capacity of 16pi cm3.what are the radius of the base and the height of the cylinder for the total surface area to be a minumum.
3.a company manufactures items at 2 dollars per item and sells then for x dollars per item.if the number sold is 800/x2 per month,find the value of x for which the company could expect to maximie its monthly profit.
4.A traveller employs a man to drive him from A to B for an hourly payment of P dollars.running costs of the car,which are also paid by the traveller,are Kv*3 dollars per hour,where vkm h*-1 is the speed,and k is a constant.find the uniform speed that will minimize the total cost of the journey.
5.if y=ax+b/x and if y=13 when x=1 and x=20 when x=2,find the values of a and b and the value of x for which y is a minimum.
感激不尽!完成保证再加分!
p.s 不是求翻译.