Question

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You have 92 feet of fencing to enclose a rectangular plot that borders on a river. If you do not fence the side alongthe river, find the length and width of the plot that will maximize the area.

Answer 1

If length along river is y, and width =x,

2x+y = 92

a = xy = x(92-2x)

This is a parabola with roots 0,46.
So, maximum value is reached at x=23.

So, the pen is 23x46

Answer 2

sam can paddle a canoe 30km upstream in 5 hours. the return ship takes 3 hours. find the speed of canoe in still water