［急］一元二次 求最大值应用题

题目

［急］一元二次 求最大值应用题
A farmer wants to fence a rectangular field and then divide it in half with a fence down the middle parallel to one side.If 1764 ft of fence is to be used,what is the maximum area of the lot that he can obtain?
就是做一个篱笆 但是在中间讲篱笆分为两部分 篱笆总长为1764 ft 问最大面积可以为多少?

答案

设长是x宽是y,
3*x+2*y=1764
面积=x*y=x*(882-1.5*x)=-1.5*(x-294)^2+1.5*294^2
最大面积1.5*294^2=129654