Answer:down below
Step-by-step explanation:A square gives the greatest area. If the river were not there, you would divide 1700 by 4 to get a square 425 feet by 425 feet. Because of the river, add 425 feet to the side opposite the river to get a rectangle 425 feet by 850 feet.
Now for the algebra that you need.
P=2l+2w but there is only one length.
P=l+2w
1700=l+2w
1700-2w=l
A=lw
A=(1700-2w)w
A=1700w-2w2
This is a parabola that opens downward so there is a maximum point, the vertex, which is (h,k).
h=-b/2a is the "maximizing point" and k is the maximum area
-b/2a=-1700/(-4)
-b/2a=425 feet
One width will be 425 feet, the length will be (425+425)=850 feet, and the second width will also be 425 feet.
A=lw
The maximum area will be A=850*425=361,250 square feet.
Notice that if you substitute 425 into the equation A=1700w-2w2 you will get the same answer.
1700*425-2*4252
722,500-2*180,625
722,500-361,250