2. 100 & lt； X< 180 people are within this range,
(x- 100) refers to the excess number of people, and 5(x- 100) refers to the amount of money reduced by each person, and each person actually paid 1000-5(x- 1000).
So for the total monetary function F=x( 1000-5(x- 100))
Simplified to f =-5 (x 2)+ 1500x. The quadratic function goes down, and the highest point x= 150 is just in the interval.
So we can get the maximum value at this time, and bring it in to get F= 1 12500.
3. Let the length be x and the width be y xy=623.7, x.
Let the total area m be a function of the total area, as follows
M=(x-2*3. 17)(y-2*2.54)
Simplifying to m = xy-5.08x-6.34y+5.71* 2 = 612.28-5.08x-6.34y brings the original xy relationship into a unified variable.
M = 612.28-(5.08x+3954.258/x) requires that the maximum value of m, that is, the minimum value in brackets, is a tick function. The general formula only needs to make x of 5.08x = 27.900 = 3954.258/x, that is, when 27.900 is obtained, m gets the maximum value.
That is M=328.82.
Here's the process. You do the math yourself.