1.Find the dimensions of the largest rectangle that can be inscri_英语解答

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.

人气：111 ℃　时间：2020-04-05 03:27:17

解答

1.It's clear that the 4 vertices are A(a,0),B(a,√(4 - a²)),C(-a,√(4 - a²)),D(-a,0)Its area S = AD*AB = 2a*√(4 - a²) S' = 2√(4 - a²) + 2a*(1/2)(-2a)/√(4 - a²) = 2√(4 - a&...大神!!!!还差最后一道题....完了再加50分!!!!拜托拜托了!!!!a printed page of a book is to have side margins of 1cm, a top margin of 2cm and a bottom margin of 3cm. it is to contain 200cm2 of printed matter. find the dimensions of the page if the area of paper used is to be a minimum.麻烦你了!!!Assume the length of the printed area is x cm, its width is 200/x cm. The length of the whole page is x + 2 + 3 = x + 5 cm; the width 200/x + 1 + 1 = 2 + 200/x cm The area of the pater is S = (x+5)(2 + 200/x) = 2x + 10 + 200 + 1000/x = 2x + 1000/x + 210 S' = 2 -1000/x²= 0 x² = 500 x = 10√5 cm The length of the whole page is x + 5 = 10√5 + 5 cm; width = 2+200/x = 2 + 4√5 cm