Question

A rectangular plot of land is to be fenced in using two kinds of fencing. Two opposite sides will use fencing selling for $8 a foot while the other two sides will use fencing selling for $4 a foot. If the maximum allowable cost is $9600, what are the dimensions of the rectangular plot of largest area that can be fenced in? verify that you have the maximized using the second derivative test

Answer 1

if x=length of two opposite sizes and y=length of other opposite sizes then you know 2x($8) + 2y($4) is less than or equal to $9600. I think the max area is usually a square so x=y so solve for 2x8+2x4=9600 or x=400