Question

A rectangular plot of farmland will be bounded on one side by a river and on the other three sides by a​ single-strand electric fence. With 600 m of wire at your​ disposal, what is the largest area you can​ enclose, and what are its​ dimensions?

Answer 1

2x+y=400 A=xy area of farmland y=400-2x A=400x-2x^2 A'(x)= 400 -4x derivative of area with respect to x 0=400-4x find out where f ' equals 0 4x=400 x=100 A'(x)= 400 -4x A''(x)= -4 check 2nd derivative. if negative then relative max at x=100 2x+y=400 y=200 dimensions 100x200 hope it helped