fencing off a rectangular playground. two length and 4 widths, 820 ft of fencing to be used.

a. express the relationship between l, w, and total length.
2L+4W=820

b. Solve for L
2L+4W=820
2L=820-4W
L=410-2W

d. Make a quadratic using W-
A=LW=(410-2W)(W)=-2W^2+410W

c. Use this result to find the width W that maximizes the area A. Can't figure out this step...

following question is use the result for D to find the maximum area and length.

Question

fencing off a rectangular playground. two length and 4 widths, 820 ft of fencing to be used. 

a. express the relationship between l, w, and total length. 
2L+4W=820

b. Solve for L
2L+4W=820
2L=820-4W
L=410-2W

d. Make a quadratic using W-
A=LW=(410-2W)(W)=-2W^2+410W

c. Use this result to find the width W that maximizes the area A. Can't figure out this step...

following question is use the result for D to find the maximum area and length.

anonymous · Answer

I think you should take derivative of A with respect to W..

anonymous · Answer

what the heck does that mean haha